for heavy-duty vehicles final...

STUDY ON

EMISSION CONTROL TECHNOLOGY

FOR HEAVY-DUTY VEHICLES

FINAL REPORT VOLUME 5

IN-USE CONFORMITY TESTING OF EMISSION CONTROL DEVICES

CONTRACT N° ETD/00/503430 Study prepared for the European Commission – DG ENTR (Enterprise)

Joint effort by

MIRA Ltd, United Kingdom

PBA, United Kingdom

LAT/AUTh, Greece

TU Graz, Austria

TNO Automotive, Netherlands

Vito, Belgium

May 2002

EC-DG ENTR Emission control technology for heavy-duty vehicles ETD/00/503430

Volume 5 Development of proposals for in-use conformity testing of emission control devices

This part of the project was carried out by

Vito Centre of expertise

Energy Technology

Boeretang 200

B-2400 Mol

Belgium

Contact In collaboration with

Guido Lenaers

Tel. 32 - 14 33 58 14

Fax 32 - 14 32 11 85

[email protected]

TNO AutomotiveJohan Verlaak Iddo Riemersma

Tel. 32 - 14 33 58 62 Tel. 31 - 15 269 67 45

Fax 32 - 14 32 11 85 Fax 31 - 15 269 68 74

[email protected] [email protected]



0 CONTENTS

0 Contents .......................................................................................................................................3

1 Executive summary ....................................................................................................................5

2 Introduction ................................................................................................................................7

3 Approach .....................................................................................................................................8

3.1 Translation of system for cars to heavy-duty vehicles ..........................................................8

3.2 Currently used/investigated heavy-duty in-use conformity procedures ................................8

3.3 On-road emission testing for in-use conformity ....................................................................9

3.4 Applicability of in-use conformity for future technology .....................................................9

4 In-use conformity testing of emission control devices ..........................................................10

4.1 Light Duty in-use conformity ..............................................................................................10

4.1.1 Directive CAP2000 on light-duty in-use conformity in the USA ..........................................10

4.1.2 Directive 98/69/EC on light-duty in-use conformity in Europe .............................................10

4.1.3 Test programmes of the Air Resources Board (ARB) of California on in-use conformity....11

4.2 Currently used/investigated heavy-duty in-use conformity procedures ..............................12

4.2.1 Evaluation of heavy-duty in-use conformity in the USA .......................................................12

4.2.2 Evaluation of heavy-duty in-use conformity in Europe .........................................................21

4.2.3 Comparison of status of heavy-duty in-use conformity in EU and USA ...............................33

4.2.4 Differences between EU and USA heavy-duty vehicle use via WHHD engine cycle ...........33

4.2.5 Applicability of USA in-use conformity approach in EU ......................................................34

4.3 On-road emission testing for in-use conformity ..................................................................38

4.3.1 From the USA study tour .......................................................................................................38

4.3.2 Manufacturers’ vision on on-road measurement systems ......................................................38

4.3.3 Review of known on-road systems.........................................................................................39

4.3.4 Proposed equipment EPA.......................................................................................................52

4.3.5 Review of possible on-road test procedures ...........................................................................54



4.3.6 Review of heavy-duty in-use conformity systems .................................................................57

4.3.7 Financial implications ............................................................................................................58

4.3.8 Potential of on-road system use for in-use conformity testing...............................................59

4.4 Applicability of in-use conformity for future technology ...................................................61

5 Conclusions................................................................................................................................62

5.1 Momentarily no regulations.................................................................................................62

5.2 Differences between USA and EU ......................................................................................62

5.3 NTE approach looks promising ...........................................................................................63

5.4 On-road measuring needs further investigation...................................................................64

6 Recommendations.....................................................................................................................66

7 References..................................................................................................................................67

8 Acronyms and abbreviations ...................................................................................................71

9 Annexes......................................................................................................................................77

9.1 Annex 1: Results questionnaire on in-use compliance ........................................................78

9.2 Annex 2: Delivery goals of CRADA...................................................................................80



1 EXECUTIVE SUMMARY

At present there are no heavy duty vehicle in-use compliance (IUC) regulations in either the US or the

EU. However, the not to exceed (NTE) limits incorporated into the US engine certification procedure could

open the way for future IUC testing executed on a dynamometer or on-road. For on-road tests the NTE limits

are well suited, as this means that the vehicle can be operated normally in traffic (instead of following a pre-

scribed speed cycle).

Dynamometer tests offer compatibility with certification legislation, and good accuracy as well as re-

producibility. On-road testing yields better cycle bypassing resistance at equal to possibly better cost-

effectiveness (to be confirmed). OBD is not an adequate replacement for IUC testing. It is currently unclear

as to whether on board monitoring (OBM) could replace IUC testing and it will need further evaluation as

this technique develops.

In the US the vehicle has to comply with the NTE limits within a defined area underneath the torque-

rpm curve of the engine. However, remaining for the required 30 seconds within the NTE zone can be diffi-

cult and the question arises as to whether real life emissions are sufficiently well reflected in the NTE test

results. Nevertheless, the NTE approach maximises the certainty that in-use emissions are under control.

More field experience with the NTE approach will show how well the concept works and where improve-

ments and further research might be necessary.

The definition of the NTE zone and the carved out areas, the engine classification and the test method-

ology could reflect conditions in the EU. However, in the interest of harmonisation, the methodology should

be the same in as many aspects as feasible. In the long term it might be advisable to include NTE testing on

the world harmonised heavy duty (WHHD) engine test cycle. This would provide a link between the certifi-

cation cycle and in-use conformity testing as NTE testing would be common to both.

If future IUC regulations require on-board measurements specific test procedures will need to be devel-

oped. They should cover aspects such as test conditions, cycles, emission limits and should provide a link to

the certification and durability regulations.

On-road (or on-board) measurement systems to verify IUC could use the NTE concept during real world

driving conditions. However, at present, no on-road systems are available that match the demanding specifi-



cations set out by the US EPA. As the NTE limits are only 1.5 times the certification limits, on-road meas-

urement systems need to offer the same accuracy as laboratory grade systems in a suitcase package. Also, the

demand for brake specific emission figures necessitates accurate information on the torque. It may take sev-

eral years before an adequate system can be developed.

Given the amount of R&D still necessary a phase-in of on-road measurement systems may occur. It

is likely that they will be firstly used to determine real life emission data, and for the evaluation of different

technologies under real life driving conditions etc. Subsequently these systems will be developed sufficiently

to enable their use as an IUC screening tool. Finally, on-road systems may serve as enforcement tools, possi-

bly without the need for additional dynamometer measurements. Until then, the on-road systems may serve

as screening tools i.e. using dynamometer measurements as a follow-up test should the vehicle fail to pass

the on-road test (see above). As an alternative dynamometer measurements can be used for IUC tests, mean-

while evaluating the on-road measurement systems (in pilot projects) until these are ready to serve as en-

forcement tools.



2 INTRODUCTION

In this volume in-use emission conformity (IUC) of heavy-duty (HD) vehicles is investigated. IUC may

be seen as a third step in the assessment of compliance with legislation where type approval is the first step

and conformity of production the second.

For light-duty vehicles IUC is already regulated. For heavy-duty vehicles this is not the case yet. We

will investigate particular aspects that address to HD IUC:

• The measures being adopted in the United States as a consequence of the ‘Consent Decree’ to evalu-

ate their potential for in-use conformity checking in Europe.

• The potential of using on-road emission measuring equipment within the scope of a European in-use

conformity testing scheme as a means of ensuring that vehicle emissions remain within conformity

over a period of durability consistent with the requirements developed in Volume 4.

The work on IUC was split into tasks, the most important of which are listed below.

Currently used/investigated HD IUC procedures

First the IUC situation in the US is evaluated, particularly the NTE limit approach and the work car-

ried out under the Consent Decrees. Then the existing IUC programmes in the EU are discussed. Finally the

applicability of the US IUC approach in the EC is evaluated.

On-road emissions testing for in-use conformity

The potential of using on-road emission testing for IUC is evaluated. Because this is a completely

different approach compared to existing procedures the evaluation of the topic will be rather extensive, in-

volving the following aspects:

• Manufacturers’ view of on-board measurement systems

• Review of known on-board measurement systems

• Proposed equipment by the EPA

• Review of possible on-road test procedures

• Financial implications

• Potential of on-board systems for IUC testing

Finally, overall conclusions and recommendations are presented.



3 APPROACH

At this moment there are no European requirements for manufacturers of HD vehicles and engines to

ensure emission durability over a certain period and over all appropriate operating conditions. In other vehi-

cle classes and in other parts of the world however, some basic ideas about in-use conformity testing can be

found. In order to be able to evaluate these ideas properly, each one is identified together with a discussion

on advantages and disadvantages of several aspects (accuracy, costs, practicability, etc.).

3.1 TRANSLATION OF SYSTEM FOR CARS TO HEAVY-DUTY VEHICLES

For light-duty (LD) and small commercial vehicles, in-use conformity (IUC) is regulated through Di-

rective 98/69/EC. This system deals with possibilities for the manufacturer to prove the in-use conformity,

with test procedures, with the selection of test vehicles, as well as with the measures to be taken if the re-

quirements for the in-use conformity are not fulfilled.

The mechanism for enforcement of in-use conformity testing to heavy-duty vehicles should follow

that laid down for light-duty and small commercial vehicles and referenced in the type-approval framework

Directive (Directive 70/156/EEC, as amended).

3.2 CURRENTLY USED/INVESTIGATED HEAVY-DUTY IN-USE CONFORMITY PROCEDURES

Up to now IUC testing has been based on the homologation test procedure, i.e. the vehicles tested

must comply with the homologation vehicle using the same test cycle. Recent developments in the United

States focus on the real world emissions, i.e. are the emissions during actual vehicle use such as can be ex-

pected from homologation testing?

In the United States, new measures are being adopted as a consequence of the ‘Consent Decrees’.

These decrees between the EPA, the Department of Justice (DOJ) and seven engine manufacturers require

meeting the US2004 standard on NOx and NMHC emissions 15 months ahead of time. The new measures

will be evaluated. At this moment several European countries, like Germany and The Netherlands, have in-

use conformity programmes running as well. Comparing these programmes with the US situation will give

additional information. In this case, an analysis of differences between the US and EU situation will be made

with the help of experience gained by TNO Automotive in the course of a project for the development of a

World Harmonised Heavy Duty engine test Cycle (WHDC). It will provide good insight into the potential of

applying this in the EU.



3.3 ON-ROAD EMISSION TESTING FOR IN-USE CONFORMITY

One of the possibilities with high potential for in-use conformity testing is on-road emission meas-

urements. In this part several aspects of on-road emission testing will be discussed.

Opinions on in-use conformity

The information from the US visit will be analysed and the vision of the manufacturers on in-use

compliance will be presented.

Existing systems and proposed equipment

Minimum specifications will be set for the measuring equipment. Available information about existing

products will be checked for the products’ applicability. Regarding existing and future engine and

emission after-treatment technologies, test procedures will also be checked for their reproducibility

and representativity.

Practical / organisational issues

Besides the technical feasibility, the practical feasibility will be assessed. This includes such topics as

time necessary for testing, necessary test infrastructure apart from the measuring equipment (tests on

public road, private proving ground, chassis-dynamometer, ambient conditions during testing, etc.).

Financial implications

Available cost estimations will be given for in-use conformity testing.

Potential of on-road system for in-use compliance

Based on the information gathered, the potential for using on-road emission measurement for in-use

compliance will be evaluated.

3.4 APPLICABILITY OF IN-USE CONFORMITY FOR FUTURE TECHNOLOGY

As this project is focussed on the emission control technology, the future after-treatment devices and

their control strategies should receive special attention as well. Most of these devices are very sensitive to

transient behaviour of the engine, and in some cases (e.g. a particulate filter) a shift in time is introduced be-

tween the moment emissions are produced in the engine and when they are released from the exhaust. The

influence these effects have on a test result cannot be neglected, and certainly need appropriate attention.



4 IN-USE CONFORMITY TESTING OF EMISSION CONTROL DEVICES

4.1 LIGHT DUTY IN-USE CONFORMITY

For light-duty, in-use conformity systems are being applied both in the USA and Europe. In the fol-

lowing an overview of some systems is given.

4.1.1 Directive CAP2000 on light-duty in-use conformity in the USA

The Environmental Protection Agency (EPA) in the United States of America has promulgated, via

the Federal Rule 40CFR86, regulations for engines and vehicles that limit exhaust emissions. To arrive at

this legislation very extensive research was carried out. All stakeholders were involved in the decision proc-

ess that resulted in the final rule.

In this legislation in-use conformity (IUC) is only required for light-duty (LD) gasoline vehicles. For

this the Compliance Assurance Program 2000 (CAP2000) is applicable. This part of the federal rule

40CFR86 prescribes how light-duty vehicles have to be checked for their in-use conformity. There are no

requirements for heavy-duty engines/vehicles as is mentioned in § II.C p. 59910 of the mentioned final rule

[1].

4.1.2 Directive 98/69/EC on light-duty in-use conformity in Europe

In-use conformity has just been introduced in the EU legislation for passenger cars (stage Euro 3).

Some details are still under discussion, and experience with the legislative approach has still to be gathered.

Directive 98/69/EC requires manufacturers of passenger cars and light commercial vehicles to ensure

that the emissions performance of their vehicles is maintained while being used by their customers up to a

period of 80,000 km or five years of use, whichever is the sooner. From 1 January 2005 the obligation will

increase to 100,000 km or five years. This is checked on the basis of comprehensive information supplied by

the manufacturer to enable the authority to audit the information. If the information is not sufficient the au-

thority may request additional information. If still not sufficient, the authority may request a sample of in-use

vehicles to be taken for full emissions testing to assess conformity. If conformity is not confirmed, a recall

plan may be initiated to require the correction of emission system faults on the vehicles found to be at fault.



In a number of countries investigations were conducted into IUC testing for light-duty vehicles [2, 3,

4, 5]. The information that can be gathered from these projects can be useful in defining the IUC testing for

heavy-duty vehicles.

An in-use conformity programme was carried out by the Umweltbundesamt (UBA) in collaboration

with similar programmes in The Netherlands and Sweden for light-duty vehicles. The UBA states that the

IUC test shall be executed by an independent party [2].

Since 1991 an in-use conformity programme for light-duty vehicles is running in Sweden. No infor-

mation was available about this programme when writing the report.

4.1.3 Test programmes of the Air Resources Board (ARB) of California on in-use conformity

The ARB is currently conducting two separate ongoing in-use vehicle test programmes [6], the ‘In-

Use Conformity Programme’ and the ‘In-Use Vehicle Surveillance Programme’.

Each of these programmes is similar as to which vehicles are borrowed from the public and tested for

exhaust and evaporative emissions at the ARB's Haagen-Smit laboratory in El Monte. However, the data

generated from these programmes are utilised for different purposes.

The ARB's ‘In-Use Conformity Programme’ is a key strategy to aid California in meeting ambient air

quality standards. The goal of this programme is to ensure that manufacturers' vehicles meet emissions stan-

dards throughout their useful lives. To accomplish this task, the ARB seeks a limited sample of vehicles from

a given engine family and duplicates the manufacturers' vehicle emissions certification tests. The vehicles are

procured, restored to the manufacturers' specifications, and tested in accordance with the Code of Federal

Regulations. ARB and the manufacturers' representatives are present to oversee all aspects of the test pro-

gramme. Should a non-conformity situation occur within a given engine family, the ARB will work with the

manufacturer to correct the problem on all affected vehicles. The corrective action is usually in the form of a

state-wide recall in which the manufacturer will notify all affected vehicle owners and state when and where

to seek the recall repair. The cost of the repair and service is free to the vehicle owner.

The primary objective of the ARB's ‘In-Use Vehicle Surveillance Programme’ is to determine a fleet

"snapshot" of baseline emissions for the mobile source emissions inventory. Secondary objectives include

the evaluation of present and future emission control programs. ARB's current programs include:

1. Evaluating the cost effectiveness of the Smog Check Program.

2. Gathering information on deterioration rates of emission control equipment for in-use vehicles.

3. Evaluating evaporative emissions.

4. Gathering chemical by chemical (speciated) exhaust and evaporative profiles for in-use vehicles.



5. Evaluating experimental vehicle test cycles.

The above mentioned programs are voluntary and mainly on cars. In 2000 a limited number of cars (4

as opposed to 40 in 1999) were tested. Those vehicles had been driven less than 90,000 miles (145,000 km).

4.2 CURRENTLY USED/INVESTIGATED HEAVY-DUTY IN-USE CONFORMITY PROCEDURES

An in-use conformity system for heavy-duty vehicles differs from a light-duty system. For light-duty

vehicles, emission data are given in g/km, as required by the vehicle homologation procedure. For heavy-

duty vehicles, emissions have to be measured in g/kWh, as a heavy-duty engine can be found in many differ-

ent heavy-duty vehicles each aimed at a particular use. Thus the emissions are expressed as brake specific.

Consequently, IUC for light-duty cannot just be copied to heavy-duty but needs adaptation. It is necessary

for heavy-duty vehicles to know the engine load, for example by acquiring the engine torque. Measuring the

engine torque in a vehicle however is quite challenging.

So, investigations on heavy-duty in-use conformity systems are ongoing.

4.2.1 Evaluation of heavy-duty in-use conformity in the USA

Up to now light-duty in-use conformity (IUC) testing is based on the homologation test procedure,

i.e. the vehicles tested must comply with the homologation vehicle using the same test cycle. Recent devel-

opments in the United States focus on the real world emissions, i.e. the emissions during actual vehicle use.

These may differ from homologation testing as it is defined now.

In this paragraph we will first discuss the not-to-exceed (NTE) limit approach. This may be a useful

tool in defining test procedures for IUC testing.

4.2.1.1 The not-to-exceed (NTE) limit approach

Up until now, test cycles with a well defined torque and engine speed profile were used to control

whether the engines manufactured fulfilled the requirements on emissions. This enabled the engine manufac-

turers to optimise their engines on emissions for these test cycles. For the engine loads that were not defined



in the test, no emission limits were applicable. As a result, real world emissions could be higher than the

emissions that were intended to be achieved by introducing the limits. To cope with this problem, the not-to-

exceed approach was introduced.

The NTE procedures apply under engine operating conditions (within the range specified in the NTE

control area) that could reasonably be expected to be seen in normal vehicle operation and use [7]. The NTE

procedure defines limited and specific engine operating regions (i.e. speed and torque conditions, indicated

as the NTE control area, see figures 1 and 2) and ambient operating conditions (i.e. altitude, temperature, and

humidity conditions) which are subject to the NTE emission standards. If the temperature is outside the range

13°C and 51°C, or the humidity is outside the range from 7.14 to 10.71 g H2O/kg dry air, than correction fac-

tors are allowed (below 1675 m altitude). The engine speeds A, B and C that are mentioned in the figures

comply with the European Steady state Cycle (Euro 3).

Emission results from this test procedure, integrated over a time window from 30 seconds, must be

less than or equal to 1.5 times the Federal Test Procedure (FTP) standards for NOx, NMHC, and PM. The

new NTE requirements are phased in starting with the 2007 model year and are consistent with the new FTP

standards.

Figure 1

NTE Zone for Heavy-Duty Diesel Engines -- C Speed < 2400 rpm

speed C = nlo + 0.75*(nhi-nlo), nlo at 50% Pmax, nhi at 70% Pmax

(PM carve-out not applicable in Final Rule)



Figure 2

NTE Zone for Heavy-Duty Diesel Engines -- C Speed > 2400 rpm

speed C = nlo + 0.75*(nhi-nlo), nlo at 50% Pmax, nhi at 70% Pmax

(PM carve-out not applicable in Final Rule)

This approach must ensure that no excess emissions occur in points of the map that are not covered by the

standard type test procedure and/or under circumstances differing from those of the type approval test. It is

also meant as a safeguard against so-called ‘defeat devices’ and/or ‘irrational control strategies’. As the cur-

rent approach in the US is to make use of the ‘control area’ as defined in the current European legislation for

heavy-duty engines this would link the European and US legislation.

Comments on NTE from parties involved

When the NTE approach was proposed by the EPA, engine manufacturers argued that the NTE lim-

its were not appropriate due to several aspects. EPA has adapted the proposal based on the comments that

were made [8]. The aspects that were stated to oppose the NTE-approach were the following:

• The impact of new technologies have not been considered in this regulation

• due to the inherent variability of emission maps of HDDE’s, the limit that results from 1.5 x FTP

limit (1.25 for 2002 under the Consent Decrees, cfr. 4.2.1.3) cannot be achieved for all operational

conditions (e.g. low engine speed, high load)

• it was not demonstrated that the limits are technologically feasible

• high brake specific emissions at low engine speeds are not taken into account



• to avoid measurement of emissions in a critical operating condition for the engine, one should con-

sider the overall emissions

• condensation and corrosion problems in the intake system (durability)

• problems in achieving PM limits using after-treatment and formation of sulphate

A number of aspects that were raised by the manufacturers against the NTE approach can already be

met today (January 2002). A number of engine manufacturers have demonstrated that they can comply with

90% of the NTE area applying cooled EGR, advanced turbo-charging systems and high pressure electroni-

cally controlled fuel injection. Some aspects cannot be met today, but can be overcome within the timeframe:

• emissions under high load situations

• high temperatures of blower

• controllability of the emission control systems (actuators)

• availability of appropriate sensors

• condensation and corrosion issues

• emission of particulates (PM) when using after-treatment and forming of sulphate

To overcome these problems, the legislative requirements will become compulsory phased in over time and

deficiency provisions are included in the NTE standard.

EPA stated that all the NTE standards will have to be met by model year 2007. In 2010 all vehicles

have to comply without exception.

4.2.1.2 EPA’s research on in-use conformity

At the moment the EPA is carrying out a program on in-use conformity for heavy-duty vehicles [9].

One of the purposes of this program is to demonstrate the feasibility of on-road testing for heavy-duty trucks

and buses. Also it is investigated whether the NTE approach can be used as a conformity tool. The measure-

ments that were executed in this project focussed on NOx emissions. More information is given below.

On-road measuring

On-road measuring is carried out with mobile measuring equipment. The purpose of this is to evalu-

ate whether it will be possible in the near future to measure exhaust emissions in vehicles on-road, with a

portable sampling system. This could make in-use conformity measurements more cost-effective. At this

moment, it looks to be a good approach, although improvements in the measurement equipment have to be

made.



Not-to-exceed limits

The not-to-exceed (NTE) limit approach is seen as the most appropriate way of testing IUC. This

approach ensures the control of emissions over a broad range of real-world conditions, reduces the need to

scrutinise emissions control strategies, and enables cost-effective in-use conformity monitoring.

The not-to-exceed limits are designed to apply under any engine operating conditions, that could rea-

sonably be expected to occur during normal vehicle use, under a wide range of ambient conditions. This type

of limit is therefore ideally suited for in-use conformity testing, although currently there is no requirement to

measure NTE emissions in-use.

Measurements

Based on the experience gathered during the tests, some initial conclusions could be made. Most of the

current-technology engines that were tested, complied with NOx NTE limits. Some required follow-up. Test-

ing according to the on-road NTE procedure apparently captured worst-case NOx operation. It was also con-

cluded that obscure operation was not an issue. Further it was experienced that the used test method com-

plemented Euro/FTP to ensure NOx conformity over a broad range of operation.

Further investigations

Further work is needed on improving the procurement of vehicles and the testing efficiency. For doing

the testing, it should be possible to use commercially available equipment with enhanced capabilities of user

friendliness, minimised testing time and cost, PM measurement, automated data analysis and improved over-

all accuracy. Also investigations have to be conducted into improving the understanding of uncertainty in

results. Finally quality control procedures should be standardised.

4.2.1.3 Consent Decree by Department of Justice (DOJ) and Environmental Protection Agency (EPA)

In the United States new measures are being adopted as a consequence of the ‘Consent Decree’, an-

nounced on October 22, 1998 by DOJ and EPA against 7 heavy-duty diesel engine manufacturers (Caterpil-

lar, Cummins Engine Company, Detroit Diesel Corporation, Volvo Truck Corporation, Mack Trucks, Ren-

ault Véhicules Industriels and Navistar International Transportation Corporation) [10].



A court settlement was reached between the EPA, Department of Justice, California ARB and the

engine manufacturers over the issue of high NOx emissions from heavy-duty diesel engines during certain

driving modes. Since the early 1990’s, the manufacturers used engine control software that caused engines to

switch to a more fuel-efficient (but higher NOx) driving mode during steady highway cruising. The EPA

considered this engine control strategy an illegal “emission defeat device”.

Provisions of the Consent Decree included the following:

• Civil penalties for engine manufacturers and requirements to allocate funds for pollution research

• Upgrading existing engines to lower NOx emissions

• Supplemental Emission Test (steady-state) with a limit equal to the FTP standard and NTE limits of

1.25* × FTP (with the exception of Navistar) (this test cycle is very similar to the European test cy-

cle ESC)

• Meeting the 2004 emission standards by October 2002, 15 months ahead of time (*) For vehicles >2007, the NTE limit 1.5xFTP applies

The Consent Decree also forces each manufacturer to spend $ 2,000,000,- (approx. 2,000,000,- EUR,

whereof no more than 20% in phase I and II) on an in-use testing programme. The actions are split into sev-

eral phases:

Table 1

Phasing of actions due to ‘consent decree’

Phase Action Time Limit

I

The manufacturer shall conduct engineering studies to determine the correlation, accuracy,

precision, and repeatability of existing mobile monitoring technologies. Further engineering

studies have to be included to determine the highest degree of accuracy and precision of re-

ported engine output torque achievable.

1 Sep 1999

II

The manufacturer shall develop in-use testing procedures (variety of on-road missions, variety

of seasonal conditions, variety of engine life time) to be used in connection with phases III and

IV of the in-use testing program. The test procedures shall also include identification of driv-

ing routes.

1 Nov 1999

III The manufacturer shall conduct emissions testing on a variety of its in-service diesel engines

to characterise real world emissions from such diesel engines. 1 Oct 2000

IV The manufacturer shall conduct on-road conformity monitoring on its heavy-duty diesel en-

gines. Vehicle selection procedures and data reporting requirements are set out.

West Virginia University (WVU) was contracted by the seven manufacturers to carry out the studies men-

tioned in phase I and II in the table above. An overview of the results is given in the following paragraphs.



4.2.1.3.1 Phase I

The object of this phase [11] is to evaluate the current available technologies to measure on-road emis-

sions from heavy-duty diesel engines. A survey of the available systems (15) is given. Some of the systems

that are mentioned later in this report (see 6.2.1) were not taken into account in this survey.

As a result of this study, the specifications of an On-Road Emission Measurement System (OREMS) were

given.

Table 2

Specifications of an on-road emission measurement system (OREMS)

Measuring Mass emissions of NOx, UHC (unburned hydrocarbons), CO, CO2

Exhaust flow rate

Engine speed and torque

Data acquisition Account for time lags and response functions

Design Portable

Accommodate a broad range of exhaust designs

Function accurately over a wide range of ambient conditions and varying altitudes

Additional power source (e.g. portable generator)

None of the available systems fully complied with the desired specifications.

WVU developed the Mobile Emission Measurement System (MEMS). This system cannot measure

CO and UHC. Engine torque is derived from the motor management ECU. The system was compared to the

EPA measuring system ROVER (Remote On-board Vehicle Emissions Recorder). This comparison proved

to be very difficult as the Rover unit under test was not able to deliver brake specific emissions nor to pro-

duce NTE test results. WVU added these features and thus the brake specific emissions are not unique Rover

results. However, the time based mass emissions of both systems were comparable.

4.2.1.3.2 Phase II

West Virginia University also carried out a study to develop testing procedures [12]. Several routes

(real world situations) were evaluated with a heavy-duty truck. It was concluded that during only a small part

of the route (from 20 to 50%) the load conditions of the engine were for 30 seconds within the NTE area.

A survey of vehicles from different manufacturers that can be tested on-road is given (have to be

equipped with engine ECU with appropriate protocol). The accuracy of the engine torque measurement is

limited. For the loads within the NTE area, the error is in the order of 10% for a 30 second window. A larger

window can reduce the error.



Conclusions WVU report on phase II:

• Remaining in NTE zone may fail

• Measurement results from laboratory equipment and MEMS show good agreement (maximum differ-

ence 5%), measurement results from MEMS on-road and on test bench differ less than 5% for NOx.

• Quality control/quality assurance plan is proposed

4.2.1.3.3 Phase III

During the US visit (October 2001), it became clear that this phase had not yet been started. The

manufacturers stated that they were waiting for the EPA to provide information on the measurement system

to be used.

4.2.1.3.4 Phase IV

No actions have taken place so far (January 2002).

4.2.1.4 Manufactures’ view of in-use conformity

Caterpillar stated that they develop engines to comply with NTE. The introduction of NTE limits has

required rewriting development procedures and software, and extensive testing. According to Caterpillar the

NTE will result in a 2-3% increase in fuel consumption (yet they claim to be able to meet the 2002/04 limits

with no fuel consumption penalty). In-use conformity is not yet a part of the final rule.

DDC believe that the taxpayer should pay for the cost of in-use conformity, not the engine manufac-

turers. DDC would not commit itself when asked whether the NTE limits had changed its philosophy to-

wards engine development. The company stated that it is its philosophy to meet all emission standards com-

petitively.

4.2.1.5 Averaging, banking and trading

One of the difficulties of in-use conformity checking is that the Federal regulations apply to engine

families. However, the manufacturers can use averaging, banking and trading provisions for their total pro-

duction volume. Thus if a tested engine/vehicle type exceeds the emission limits specified for that engine,

the manufacturer may compensate for this with another engine/vehicle type which produces emissions below

the limits. As long as the emissions produced by all the manufacturers’ engines (the total production volume)

are below a well defined level, the manufacturer is allowed to produce and sell these engines. As a conse-

quence the evaluation of the IUC testing can become very complicated, due to the fact that the total produc-

tion volume of an engine and vehicle manufacturer has to be considered.



4.2.1.6 Conclusion about the heavy-duty in-use conformity situation in the USA

To prepare for the actual legislation, extensive discussions have been held between the EPA, engine

manufacturers and other stakeholders. As a result of these discussions, the original regulation proposed by

the EPA was adapted. By doing so, it is possible to force the engine and vehicle manufacturers to take ac-

tions on emission control. However, in-use conformity for heavy-duty vehicles is not yet in legislation.

Consent decree

Manufacturers are awaiting the measurement system to carry out phase III of the consent decree. At

this moment it is not clear what equipment has to be used. Therefore, the original time schedule from within

the consent decree cannot be maintained.

Non-conformity penalties (NCP)

EPA introduced non-conformity penalties (NCP) as a possibility for manufacturers to cope with the

consent decree emission limits. According to this a manufacturer can produce a new vehicle or engine with-

out complying with the emission limits, but by paying a penalty. A public hearing on this will be held on the

15th February 2002. At the time of finalising the report no information on this could be found or was given

by the EPA upon our request.

In-use testing programs

The EPA is running a heavy-duty in-use conformity program. Experience shows that it will be possi-

ble to do cost effective IUC testing by using portable emission measuring system, but further investigations

and testing need to be done.

When writing this report, we were not aware of any actions by the vehicle or engine manufacturers.

Miscellaneous

Heavy-duty in-use conformity will possibly not be compulsory before 2011, as was stated during the

US visit by an EPA spokesman. It was also stated that EPA wants to be in compliance with Europe.

Averaging, banking and trading will complicate the rule making for in-use conformity.



4.2.2 Evaluation of heavy-duty in-use conformity in Europe

4.2.2.1 In-Use conformity programmes for heavy-duty

For heavy-duty vehicles no legislation exists yet, but again some or even extensive experience exists

on a national level in The Netherlands, that runs a relatively large programme (TNO Automotive, Delft), and

Germany, that runs a smaller programme (Umweltbundesamt). The testing is executed on a vehicle basis

(whereas the type approval test is on the engine) and on the basis of steady state testing (as is the current

European Stationary Cycle (ESC) test).

4.2.2.2 The Netherlands

In 1994 TNO Automotive started its HD vehicle In-Use Compliance programme at the request of the

Dutch Ministry of Spatial planning, Housing and the Environment. Until now, it has been possible to simu-

late the homologation test procedure with acceptable accuracy on the vehicle (using a chassis dynamometer),

rather than testing the engine on an engine dynamometer, as prescribed by the type approval procedure. Ad-

vantages of this methodology developed by TNO, are the cost-effectiveness and the possibility of using the

homologation test results as a reference. With the Euro 3 legislation coming into effect, new test cycles with

transient elements are added to the homologation procedure, where previously it was only a stationary test

cycle. As a result of this, the test methodology used so far no longer applies to the whole procedure. Because

it is anticipated that in the near future emissions from HD vehicles will be increasingly related to transient

engine behaviour, a transient test cycle is also important for IUC purposes.

As the current testing methodology used by TNO is not applicable for a transient engine test cycle, alter-

native options have been identified and assessed that may serve the aims and demands of the Dutch IUC

programme. Also the possible role that OBD can play for IUC purposes was evaluated. This has resulted in

the following conclusions and recommendations:

• With current and future engine technology, emissions from transient engine behaviour are becoming

increasingly important for the total of emissions produced. This calls for the need of transient ele-

ments as part of an IUC test procedure, and, for the purpose of reliable emission factors, the use of

test cycles that correspond to real-life driving conditions.

• The ETC test, being an engine based test cycle, is not suitable for IUC purposes as it is impossible to

perform a transient engine test on a HD vehicle.

• In the future, the aims of the Dutch IUC programme are best fulfilled by a stationary engine test cy-

cle on the chassis dynamometer, extended with transient elements such as an ELR for the evaluation



of compliance. For the production of emission factors, a combination with transient vehicle-based

test cycles is required.

• OBD will not fulfil all of the primary aims set for the Dutch IUC programme, so it cannot be seen as

a substitute. However, for the evaluation of compliance it can deliver a useful contribution. The role

of OBD may change in the future, if it is extended with an emission measuring functionality (OBM).

4.2.2.3 Germany

In 1998 an HD IUC test programme was set up by the Umweltbundesamt (UBA) [4]. Measurements

were carried out on a chassis dynamometer. All the tested engines complied with the regulations. It was con-

cluded that the selection and the preparation of the vehicles to be tested are important. Also the problem of

an appropriate IUC testing procedure has to be solved.

A number of alternative test methods on in-use conformity testing, were evaluated. The main diffi-

culty is the fact that the test has to be transient. The methods mentioned are:

• Removing the engine from the vehicle to do a test on an engine dynamometer is the best way to

compare with the original approval test. In practice this is rather difficult, even more so when emis-

sion reduction technologies are used (see also section 4.2.2.7).

• Putting the vehicle on a chassis dynamometer is practically very simple. However, chassis dyna-

mometers with the required power rating are very rare. Another difficulty is that transient testing will

require dynamic corrections for drive train and auxiliary losses (see also section 4.2.2.7).

• One could also perform steady state testing and correct the emission values using a dynamic map to

calculate emission factors. The question remains whether the aging of the engine or the after treat-

ment system can be simulated in this map.

• A promising solution seems to be to disconnect the drive shaft and couple it to a dynamometer. In

this situation drive train losses have still to be taken into account. Otherwise the effort is comparably

small and correlation to type approval is good.

• Another possibility is the introduction of on-board measuring (OBM) systems for emissions. When

this is the case, IUC can be seen as checking the OBM system on a temporary basis.



4.2.2.4 Sweden

For heavy-duty vehicles there is no programme known. The Swedish Environmental Protection

Agency was contacted, but no answer was received at the time of writing this report.

4.2.2.5 Manufacturers’ view

From the questionnaire sent out (see volume 1 of this final report) the following results (see annex 1

for tables) can be given on the subject of in-use conformity testing (‘manufacturers’ refers to all the respon-

dents to the questionnaire, that means vehicle, engine and component manufacturers):

• The manufacturers are not convinced of the fact that in-use conformity testing will reduce the real

world emissions.

• They state that OBD and OBM will make IUC superfluous.

• The in-use conformity testing shall be executed by the vehicle manufacturer or a type approval au-

thority. The cost issue i.e. what are the costs and who will carry them needs addressing.

• On whether the test shall be done on the road, on a chassis test bench or on an engine test bench,

most of the manufacturers disagree.

• An IUC test should occur only once in the lifetime of a vehicle, at a random (mile)age (minimum 24

months or 200,000 km).

• The parameters that have to be tested are not yet defined.

These results give a rough idea on the manufacturers’ opinion on IUC. It will surely be useful to discuss this

matter in further detail with each of the manufacturers when proposals are laid down.

In a discussion the following was stated by Mr. Signer (European Engine Alliance) on the matter of

in-use conformity. There is a major problem of ‘chip tuning’ with in-use vehicles. Apparently Volvo (one of

the first manufacturers to introduce electronics on their engines, and hence having the most experience) has

found that 10% of their trucks have the electronics manipulated to increase power output, with no regard for

the emissions. This can be done by replacing chips, reprogramming the on-board computer, inserting a de-

vice that alters the signals, etc. Thus the in-use emissions/fuel consumption performance is likely to be very

different to the theoretical performance. This raises interesting issues regarding who takes the responsibility

for in-use emissions if the engine has been tampered with. Presumably the engines are returned to the manu-

facturer’s settings if the vehicle is returned to the manufacturer under guarantee or for I/M tests.



4.2.2.6 Conclusions about the heavy-duty in-use conformity situation in Europe

Several national programmes on heavy-duty in-use conformity are running in the EU. They are based

on steady state testing executed on a chassis dynamometer. As for Euro 3 ETC and ELR transient testing has

entered the regulation. It is investigated how the IUC steady state test can be replaced/upgraded with tran-

sient elements.

4.2.2.7 Assessment of possible test procedures for IUC testing

This section as well as section 4.2.2.8 is based to a very large extent on a paper by TNO Automotive

presented at the Intertech Conference held on 15-17 October 2000 in Berlin [5]. As mentioned in section

4.2.2.2 TNO Automotive conducts a large LD and HD IUC programme for the Dutch government. Consider-

able experience has been gained with HD chassis dynamometer steady state tests. Vito has complemented

the text from its experience in on-road testing.

In October 2000 the Euro 3 legislation came into effect for new engines entering the market. The ECE

R49 13-mode stationary test was replaced by a European Stationary Cycle (ESC). This new stationary cycle

is rather similar to the ‘old’ 13-mode test, except for the location (and weight) of the mode points. The meth-

odology for measuring a stationary engine cycle on a chassis dynamometer (applied by TNO in the Dutch

IUC programme) can therefore still be applied.

Furthermore, a European Load Response test (ELR) was added to the homologation procedure to re-

strict the smoke emission during transient engine loads. If the chassis dynamometer is designed to keep the

speed of the rolls constant at varying loads, this test can also be simulated on the vehicle. Alternatively, the

test could even be done on the road, as the measurement equipment can easily be made portable (only a

smoke opacity analyser is needed for the ELR).

For gas engines and diesel engines equipped with exhaust after-treatment systems the Euro 3 legisla-

tion prescribes the European Transient Cycle (ETC). This is a dynamic engine cycle, so engine torque and

speed are defined as a function of time. Simulating this engine cycle on a (transient) chassis dynamometer

poses the following problems:

• As the ETC is an engine cycle, also gear shifting points are defined in it. The gear ratios of a vehicle will

not exactly match those of the test cycle, so the engine speed will deviate from the prescribed one after a

shift has taken place. The correction needed to compensate this speed difference will introduce an error

in the test result. Alternatively, the ETC can be tested in one gear. As a consequence, the whole driveline

then has to be accelerated or decelerated quickly in a short period. Because of the rotational inertia

within the driveline, this may cause the wheels to slip.



• As a result of inertia effects, vibration, torsion and hysteresis within the driveline it is extremely difficult

to predict the engine torque accurately from the torque on the rolls. Measuring the engine torque directly

from the engine crankshaft may be an alternative, but is quite complex at this moment.

Note that the moments of inertia of components within the driveline need to be known, either from the

manufacturer or via empirical evaluation (e.g. coast-down tests).

• The same dynamic effects also make it very hard to control the engine torque by adjusting the torque on

the rolls. The torque needed to compensate for these effects may even be of an order of magnitude higher

than the actual engine torque prescribed by the test cycle.

These problems will make a simulated ETC on a chassis dynamometer very difficult (with correspond-

ingly high inaccuracy), if not impossible. The only alternative is to dismount the engine from the vehicle,

and test it on a transient engine dynamometer. This is an undesirable method for IUC testing from the point

of cost effectiveness and practicability. The conclusion therefore can only be that the ETC, or any other tran-

sient engine test cycle for that matter, is not an appropriate cycle to be used for IUC testing. As a conse-

quence, the emission values determined for the ETC during homologation cannot act as a reference for IUC

testing. The market share of HD vehicles with gas engines or diesel engines with exhaust after-treatment sys-

tems under Euro 3 legislation is expected to be quite low. Therefore, the problem of the ETC being unfit for

IUC testing purposes will be only a real issue when Euro 4 legislation comes into effect (2005).

With current and future engine technology, emissions from transient engine behaviour are becoming

increasingly important as to the total of emissions produced. So, the information that an in-use vehicle com-

plies during a transient test cycle is more valuable than compliance with only a stationary test cycle. For the

determination of emission factors a transient vehicle test cycle is more preferable, especially if this repre-

sents the real-life operating conditions for the vehicle type observed.

In the following section a number of possible options for IUC testing will be identified.

4.2.2.8 Options for practical IUC testing of HD vehicles

The benefit of a transient IUC test procedure has been indicated in the previous paragraph. However,

the ETC, or any other engine based transient test cycle, can obviously not be used for this purpose, so an al-

ternative procedure has to be thought of. Any alternative IUC test procedure also brings the need for a refer-

ence, in order to evaluate measured emissions during the vehicle life. If the IUC test were to be legislated,

the homologation test procedure could be expanded with this test in order to provide the reference. In this

paragraph the assumption is made that, where necessary and feasible, the corresponding legislative arrange-

ments for expanding the homologation test procedures have been made for each option.



The options that will be discussed can be classified in two groups:

• Laboratory tests: a vehicle is driven to a test laboratory, where instrumentation and testing take

place in a conditioned environment

• On-road tests: a vehicle is instrumented in a laboratory, and tested on the road or a circuit

Generally, a test in a laboratory will have a better reproducibility and accuracy because of the conditioned

environment and the higher standard of the measurement equipment. On-road tests, on the other hand, have

the advantage of lower investment costs.

Now the options will be identified and briefly described. This list may not be complete, but the authors

have only considered the most promising options. Simple test methods that for example only observe the

emitted smoke have therefore not been taken into account. Other methods can be seen as a variant of the op-

tions mentioned here.

Laboratory tests

1. Transient engine test cycle

The engine is dismounted from the vehicle, and tested over a speed/torque-time test cycle on an engine

dynamometer. This option is already identified as being costly and impracticable for setting up an IUC

programme of substantial size.

2. Stationary vehicle engine test cycle

This is the method used for the current IUC programme in the Netherlands, in which a stationary engine

test cycle (e.g. the ESC) is tested on a vehicle on a chassis dynamometer. Some transient elements need

to be added (where the dynamometer is suitable for this), in order to evaluate basic transient perform-

ance. An ELR test is a good example of such a test.

3. Transient vehicle test cycle

This is a speed-time test cycle that is driven on a HD transient chassis dynamometer. Such a facility is

not widely available; at this moment there are only three in Europe.

On-road tests

4. Transient vehicle test cycle

A speed-time test cycle is driven on the road. If other traffic is driving on this road as well, it will proba-

bly conflict with the test cycle. So an empty road (e.g. test track or circuit) is required for this test. The

emission measurement equipment is carried on board the vehicle.

5. Vehicle cycle with target speeds

This is also a speed-time test cycle, but with periods in which a constant target speed is defined, instead

of an exact prescribed speed pattern. The acceleration is left to the ability of the vehicle. Such a cycle is



easier to carry out on a road with other traffic present, but a test track is desirable. The emission meas-

urement equipment is carried on board the vehicle.

6. Real-life arbitrary cycle with Not-To-Exceed limits

The idea of this method is to have a set of limits in the legislation that may never be exceeded during any

driving condition. Therefore, the test driver can drive normally in traffic, without having the restrictions

of a test cycle.

7. On-Board Diagnostics system

In principle, OBD is not a method for IUC testing, but it can be used as an instrument to prevent engines

from malfunctioning. Assuming the emissions from a properly functioning engine correspond with those

of the homologation engine, it can be seen as a method for obtaining compliance. The reason to include

OBD in this list is therefore to illustrate the contribution that it may deliver towards IUC testing.

If in the future OBD would also be capable of measuring emissions (On-Board Monitoring; OBM), its

role towards IUC testing would have to be re-assessed.

For the last two options there is no need to extend the homologation procedure with an additional test

to serve as a reference cycle; in case of option 5 only a set of NTE limits has to be legislated. Legislating a

vehicle-based test cycle to serve as a reference cycle (options 3, 4, and 5), will prove to be very difficult. HD

engines appear in a variety of different vehicle types and drivelines. A number of vehicle related aspects that

have an influence on the test results, are therefore hard or even impossible to prescribe in a test procedure

(weight, driving resistances, driveline efficiencies, gear ratios).

In order to make a comparison between each of these options, their ability to serve the aims and de-

mands of an IUC programme is assessed. In the table below the results are shown. Indicated per option is the

extent to which it serves the aim or demand, going from ‘very well suited’ (+ +) to ‘unsuitable’ (- -).



Table 3

Table with assessment of pos-

sible testing

Lab Tests On-road

Tr

ansi

ent e

ngin

e te

st

cycl

e on

eng

ine

dy-

nam

omet

er

Stat

iona

ry v

ehic

le te

st

cycl

e on

cha

ssis

dy-

nam

omet

er

Tran

sien

t veh

icle

test

cycl

e on

cha

ssis

dy-

nam

omet

er

Tran

sien

t veh

icle

test

cycl

e

Targ

et sp

eed

cycl

e

Rea

l-life

with

NTE

limits

OB

D sy

stem

Legislation compliance ++ + - - - - +

Emission factors + 0 + 0 0 0 --

Maintenance effects + ++ ++ + + - 0

Cycle bypassing + - + + + ++ -

Cost effectiveness -- + 0 + + + ++

Practicability -- 0 + 0 0 + ++

Reproducibility, accuracy,

comparative ++ + + - - -- 0

The following will motivate the assessment for each of the aims and demands separately.

Legislation compliance

A first condition for evaluating compliance is that the test itself is suitable to be legislated. As it was

concluded that HD engines are applied in a variety of vehicle types and drivelines, thereby practically pre-

venting a vehicle-based test cycle from being legislated, none of the options that make use of a speed-time

pattern are appropriate to evaluate compliance on.

Obviously a transient engine test cycle fulfils the requirements of legislation compliance best. In this

respect, a stationary engine test cycle can only be considered as an option if transient elements are added to

the test, derived from the transient engine test cycle.

Another important aspect is that the test needs to be accurate and reproducible. Because of the condi-

tioned environment and the more accurate emission measurement equipment, the laboratory tests are more

appropriate than on-road tests. For the arbitrary cycle with NTE limits and OBD, reproducibility is in fact no

issue as the limits set may not be exceeded under any driving condition. Still, the laboratory tests have a

higher ranking, as they not only show if an engine complies, but also provide better insight into the ratio of



test results with respect to the homologation results. Moreover, OBD can only check a number of engine pa-

rameters, but is no absolute guarantee for compliance of emissions.

Emission factors

For the determination of representative emission factors (defined as a statistically correct average

emission value for a certain group of vehicles) the tests used should be representative for real-life driving

conditions. Also, the level of reproducibility and accuracy of these tests should allow the investigation of the

influence of different parameters on the emission performance of the vehicle type under study for the pur-

pose of bottom-up emission modelling. Such an emission model can provide representative emission factors,

and serves as a tool to calculate the effect of traffic measures, introduction of new emission reduction tech-

niques etc.

These purposes can be served best by either a dedicated vehicle test cycle, driven on a HD chassis dy-

namometer, or a dedicated transient engine test cycle on the engine dynamometer. In both cases the labora-

tory environment allows the variation of one parameter while keeping the others constant. The influence of

this parameter can be determined in this way. It should be noted that the number of influencing parameters

for future more complex Euro 4 and 5 vehicles will probably increase. The resulting test matrix to investigate

the effect on emissions of each of these parameters will be accordingly large and costly to execute. There is

however no alternative. Also, the more dedicated the engine or chassis dynamometer cycle the better the re-

sulting emission factor will be. The large variety in HD vehicles and in HD engine use does not facilitate the

elaboration of one dedicated cycle which is valid for all. In practice the cycle will hardly ever be fully dedi-

cated to the vehicle thereby reducing the accuracy of the emission factor to the extent of imperfection of the

cycle. As a result the highest mark (++) can not be given in Table 3.

The vehicle test cycle can also be driven on the road but will produce less accurate test results due to

the unconditioned testing method. This is also valid for the target speed cycle. Emission factors measured

on-road from a test cycle with NTE limits give a good impression of real-life emissions, but these are not

necessarily representative for real-life vehicle use. Due to the fact that these results are not reproducible, they

will not allow for bottom-up emission modelling. However, a database covering all of the NTE test results

will probably yield an average result which can be seen as a representative in-use emission factor (assuming

that all relevant influences on emissions are equalised by the high number of test results). If only a selection

of the database can be used for a detailed investigation of a particular problem, the number of test data de-

creases (as well as the equalising effect), resulting in less accuracy. Examining the influence of a particular

parameter by keeping the others constant is not possible. Note also that for emission factor purposes all test

data need to be used and not just the ones from within the NTE area. Otherwise the result is not representa-



tive as the engine operates considerable time out of the NTE area (see sections 4.2.5.2 and 4.2.5.3). So the

three on-road ‘cycle’ options got a ‘0’ as mark in Table 3.

Finally, it would be an asset to emission factor work if laboratory and on-road test results would com-

plement each other.

Assuming that OBD at this moment can only inform about the status of the engine (On-Board Moni-

toring is not yet technically feasible), it delivers no contribution to the determination of emission factors.

This situation may change if in the future emissions can be measured accurately by OBM. As the emissions

due to transient vehicle use are becoming more important, the relevance of a stationary engine for the pur-

pose of emission factors is only limited.

Maintenance effects

To research the effects of maintenance on emissions, laboratory tests have the advantage of being ac-

curate and reproducible. Therefore, the resulting effects on emissions can be attributed to re-adjustments

made to the engine. The lower reproducibility of on-road tests is preventing the correlation of the resulting

effects towards the state of maintenance (especially for the target speed option). OBD does not provide any

direct relationship between maintenance and emissions, but can give valuable information about the defect

history of the vehicle.

Cycle bypassing

The detection of cycle bypassing strategies conflicts with the demand for reproducibility, as this

makes it easier for the engine management system to recognise a test cycle. The fact that on-road testing

methods are never exactly identically, prevents the use of cycle bypassing strategies. OBD is not able to de-

tect cycle bypassing, assuming that it is only checking the engine behaviour. Besides, the manufacturer de-

velops both the OBD system as well as a potential bypassing strategy. The role of OBD in detecting cycle

bypassing may change if in the future emissions can be checked by an OBM system.

Cost-effectiveness

The laboratory tests will demand for high investment costs in facilities and equipment, especially for

transient test facilities. Once this investment is made, the costs per vehicle test are dependent on the number

of tests i.e. the more tests the lower the costs per single test. This does not account for the transient engine

test, which asks for the engine to be dismounted from the vehicle, instrumented, and installed on the engine

dynamometer.

For the on-road options only portable emission measurement equipment is required, which involves

relatively low investment costs as long as the life time and service costs are comparable to laboratory equip-



ment. This remains to be proven. If needed a test track to perform the on-road test cycle can be hired. The

costs per individual vehicle test will be largely dependent on the time elapsed to instrument the vehicle.

An analysis executed by the EPA [9] on a dedicated on-road system gives an average instrumentation

time of two hours followed by a maximum of two hours of measurement. This presents a cost effective ap-

proach. The ultimate goal -as defined in EPA’s call for a Cooperative Research And Development Agree-

ment (CRADA) (see section 4.3.4)- is to reduce the instrumentation time to half an hour. Under the NTE op-

tion the measurement time can be extended as the vehicle will be monitored during its normal exploitation.

When this goal is achieved on-road measurements will become very cost effective. Before and after the test-

ing the vehicle stays in exploitation as the measurement system is transported to the vehicle. This is opposite

to laboratory measurements. However, there is also a cost associated with transporting the measurement sys-

tem. Furthermore, cost-effectiveness will be influenced by the level of use that can be made from the test

results of the different options. If for instance -next to IUC- the result from one option can also be used for

e.g. emission factor work this yields a considerable positive effect on cost-effectiveness. Overall, in the fu-

ture on-road will most likely be more cost effective, if the CRADA goals can be met. Given this analysis the

options ‘Stationary engine test cycle on chassis dynamometer’ (possibly with limited transient parts) and the

‘three on-road cycle options’ have been given the same marks. When in future more cost data are available a

new analysis will show the most cost effective option.

OBD is very cost-effective from a government point of view, as it is paid for by the customer. It only

needs to be checked for proper operation and a possible indication of malfunctioning.

Practicability

Performing a transient engine test by dismounting the engine from the vehicle is already considered to

be very impracticable. The laboratory transient vehicle test cycle, on the other hand, is relatively easy to per-

form, because little or no instrumentation is needed on the vehicle.

The on-road measurements require more instrumentation, and the installation of the on-board emission

measurement equipment. Depending on the test method the vehicle is driven to the test circuit or is just

driven on public roads. This is the case for the real-life arbitrary cycle with NTE limits.

For the vehicle test cycles it has to be mentioned that the development of the dedicated test cycles will

have to be carried out before introduction of such a testing method.

Accuracy, reproducibility, and comparison with homologation test results

Generally, the laboratory tests have an advantage over the on-road tests because of the conditioned en-

vironment.



For OBD and the real-life arbitrary cycle with NTE limits these demands are of less importance, as for those

options there is no reference to homologation test results.

The assessment table and the accompanying motivations, lead to the following conclusions:

• Generally, the best choice of test method depends on the particular aims the legislator has set for the IUC

programme. The choice can be derived from Table 3. Overall, laboratory tests offer better compliance

with certification legislation, better research of maintenance effects on emissions and better accuracy as

well as reproducibility. On-road testing yields better cycle bypassing resistance at equal to possibly bet-

ter cost-effectiveness (to be confirmed).

• Vehicle based test cycles are not suitable for legislation purposes, as HD engines appear in a variety of

different vehicle types and drivelines.

• Evaluating the legislation compliance can only be actively monitored by laboratory tests that use an en-

gine based test cycle. Alternatively, OBD systems can be applied, but they can only check a number of

engine parameters, which is no guarantee for compliance.

• From the viewpoint of reliable emission factors the transient laboratory tests are more suitable for the

elaboration of bottom-up emission models that enable detailed emission studies, whilst on-road NTE

emission tests have the advantage of providing real-life in use emissions. A possible benefit can be

gained if a combination of transient laboratory tests with complementary on-road test results (for valida-

tion purposes) is applied.

• If the objective of the IUC programme is to obtain detailed information concerning maintenance effects,

the best alternative is to use laboratory tests, for reasons of accuracy and repeatability.

• The role of OBD is one that can deliver a useful contribution, but cannot replace IUC testing. This role

may change if OBD is extended with an emission measuring functionality (OBM).



4.2.3 Comparison of status of heavy-duty in-use conformity in EU and USA

In the USA, engine and vehicle manufacturers are forced by the ‘Consent Decrees’ to undertake ac-

tions to prepare for the coming directives on in-use compliance for heavy-duty vehicles.

In Europe national programmes on IUC are running in The Netherlands and Germany. No actions are

enforced on the manufacturers yet.

4.2.4 Differences between EU and USA heavy-duty vehicle use via WHHD engine cycle

It was planned that an analysis of differences between the USA and EU situations would be made with

the help of experience gained by TNO Automotive in the course of a project for the development of a world

harmonised Heavy Duty (WHHD) engine test cycle. This would provide good insight into the potential of

applying this in the EU.

Due to the fact that the project on the WHDC is not yet finished, limited data are available [13]. De-

tailed information could not be incorporated in this report. Some main results relevant to this study are:

• The average engine power over the combined idle and power delivery modes is 30% for the EU,

26% for the US and 20% for Japan (World: 26%).

• Motoring and idle modes amount up to 40% of total time

• the region in between idle and 30% of maximum power amounts up to 25% of total time for the EU

and 40% for the US (World: 30%)

• for the remaining 35% in the EU and 20% in the US (World: 30%) the engine delivers more the 30%

of its maximum power. So the NTE carve-out below 30% of maximum power (see section 4.2.1.1)

eliminates 70% (World) of all engine modes.

• A World Harmonised Steady state Cycle (WHSC) is under development as a basis for IUC. The test

should be incorporated in the certification testing to serve as reference.



4.2.5 Applicability of USA in-use conformity approach in EU

4.2.5.1 In-use conformity testing based on the NTE approach

As explained in sections 4.2.1 and 4.2.2 there is no HD IUC regulation in place either in the USA or

in the EU. Looking at the upcoming Euro 4 regulation, in the EU a slightly adapted LD Euro 3 IUC system

is proposed. In the USA no IUC regulation is incorporated in the 2004 and 2007 sections of the Code of

Federal Regulation (40CFR86). However, the NTE limits are incorporated as part of the engine certification

procedure. This could possibly open the way for a future IUC based on these NTE limits. The actual IUC

NTE testing could be executed on a dynamometer or on-road. For on-road tests the NTE limits are well

suited, as this means that the vehicle can be operated normally in traffic (instead of following a prescribed

speed cycle). This USA situation is here referred to as USA IUC “approach”. In the following both the ap-

plicability of this approach as such and as within the EU is discussed.

4.2.5.2 Not-to-exceed limits in general

The NTE limit definition enforced on a HD vehicle looks to be an ideal tool for IUC. Within rela-

tively wide intervals for environmental parameters such as temperature, relative humidity, etc. the vehicle

has to comply with the NTE limits for the defined NTE control area under the torque-rpm curve of the en-

gine (see section 4.2.1.1). As the NTE limits are only 1.5 times the FTP certification limits some areas under

the torque-rpm curve are carved out i.e. those areas with high brake specific emissions. Otherwise the limits

are not feasible. If the engine had to fulfil NTE limits in each 30 second window within the NTE control

area including the carve-outs a few seconds in these regions could cause the engine to fail passing. As the

engine was believed to stay only a brief time in the carved out areas during its normal operation, emissions

out of these areas would contribute little to its real-life emission behaviour. This would justify the carve-outs.

Comments on the test procedure

In phase II of the work carried out by West Virginia University under the Consent Decrees on-road

testing revealed that remaining for 30 seconds within the NTE zone can be quite difficult (see section

4.2.1.3.2). The resulting low NTE availability poses a problem in itself, in that many measurements from

within the NTE zone have to be rejected. The question arises if in this way all real-life emissions are suffi-

ciently well ‘weight reflected’ in the NTE test results. Clearly this cannot be the case. Let us take the exam-

ple of the emissions carve-out under the 30% Maximum Power curve in the torque-speed diagram. If an en-

gine frequents this region regularly, not only will the NTE availability be low, but also many measurements

just above the 30% curve will be rejected and thus underweighted. If this concerns regions under the NTE



zone with relatively high brake specific emissions, then NTE testing will not reflect what it has been in-

tended for. Moreover, if an engine manufacturer ‘adapts’ his engine so as to frequent more the carve-outs

more, with high brake specific emissions, then he can influence the final results in his favour. This effect

can be enhanced by the kind of cycle that is driven.

Another approach to the NTE limits could be to minimise the carve-outs in combination with higher

limits, i.e. more then 1.5 times the FTP limits. Alternatively, the carve-outs could become regions with

smaller weight factors assigned, thus countering for the higher brake specific emissions. This would give a

much higher NTE availability and a better weighted result, thereby leaving less room for engine “adapta-

tion”.

Also the NTE 30 second window must be evaluated. A smaller window might be undesirable, because a

high but short emission event can cause the engine to fail the test. A too large window on the other hand

might attenuate transient emissions too much.

More field experience with the NTE approach will show how well the concept works and where im-

provements and further research might be necessary. Still it is believed that the NTE limits offer a good so-

lution for in-use conformity checking. Given a good approach the engine is tested under a wide variety of

in-use conditions thus maximising the certainty that the in-use emissions are under control.

4.2.5.3 NTE in Europe

The USA IUC approach when applied in the EU might need adaptations related to the differences in

vehicle use between the USA and the EU (see also further ‘Road load compared to NTE area’). The NTE

concept itself is believed to be universally applicable. However, the definition of the NTE zone and the

carved out areas, the engine classification and the (test) methodology could be specific for the EU situation.

NTE methodology

The methodology should be as alike as possible in as many aspects as feasible. Given the fact, that

in the USA the NTE limits are FTP limit based, this would mean that in the EU the base could be the ETC

cycle. If the ESC could be the base in both the USA and EU this would lead to further harmonisation of

emission regulation. The Euro 3 ESC is incorporated in the CFR as Supplemental Emission Test (SET) for

future regulation. The ESC however is a stationary test cycle, thus leading to a situation where limits for

dynamic NTE testing would be based on limits of a steady state test.

A way out of this is presented by the World Harmonised Heavy Duty (WHHD) engine test cycle.

This cycle is dynamic and intended for universal use. Moreover, it is designed to reflect real-life engine use.

In this way in-use testing limits are based on limits of a dynamic and realistic certification cycle which seems



a logical approach. Furthermore, it might be advisable to extend the certification testing to include NTE test-

ing along the WHHD cycle. This yields a firm link between certification and in-use conformity testing as

NTE testing is a factor common to both. It is important to note that NTE testing within the certification pro-

cedure excludes the use of stationary tests such as the ESC to link the NTE limits to. The NTE testing is in-

trinsically dynamic and of course not designed for use with a steady-state cycle.

The path along the WHHD cycle presents a long term approach. It might well take until 2012-2015

before a concept like the WHHD cycle is incorporated in the USA, Japanese and EU emission legislation.

This 10 years plus timeframe may look like a long period, however it must be taken into account that the US

2007 and Ero 5 (2008) regulations are already in place. The WHHD cycle then has to be fitted into the dif-

ferent new regulations. A lead time has to be given to the engine manufacturers – a four years minimum pe-

riod by legislation in the USA – to let them prepare for the new situation. Thus a 10 years plus timeframe

seems to be realistic.

Chassis and engine dynamometer versus on-road measurements

In section 4.2.2.8 an extensive assessment covering different aspects of possible test methods for

IUC is presented.

In the light of world wide harmonisation a common set of specifications for on-road systems should

be used across the USA and the EU. Also, the test protocol should be universal.

Engine classification

The engine classification within the USA NTE approach (see section 4.2.1.1) is based on the C speed

with 2400 rpm as spill. Whether this is applicable for the EU needs further investigation. A comparison

needs to be made between the USA and EU HD engines. However, as the USA upcoming regulation in-

cludes the EU ESC cycle as a Supplemental Emission Test (SET) and as the definition of the C speed is

identical to ESC and NTE, not many problems seem to arise as to differences in engines. Therefore, engine

classification should pose little problem.



Road load compared to NTE area

The definition of the NTE zone and carved out areas under the torque-rpm curve of the engine is

given some general thought at the beginning of this section. The applicability in the EU is questionable. In

particular the carve-out below the 30% maximum power curve needs attention. In the EU -and even more in

the US- heavy-duty engines mounted in on-road vehicles operate for a considerable time underneath this

curve [13] (see section 4.2.4). This is especially true for MHDDE and LHDDE. The data gathered in the

study on the WHHD cycle should be examined to help propose a new carve-out at a lower than 30% maxi-

mum power curve. Unfortunately these data are not public at the time of writing this report. It might be

necessary to have separate definitions for this carve-out for engines with C speeds below 2400 rpm and for

those above.

Further actions

The items of this section should be the subject of discussions with the engine manufacturers and the

EU member states, for example within the Motor Vehicle Emission Group (MVEG) that is chaired by the

EC. Thus a common European approach can be developed. Moreover, in the light of harmonisation of emis-

sion regulations, the EC and the US EPA should confer on their intended approaches to IUC.

It should be stressed that the ideas, advice and comments in this section of the report (on USA IUC

applicability in general and in the EU) are developed by Vito from experience in on-road in-use emission

measurements. Of course this does not mean that no other, maybe better approaches are possible. The dis-

cussion surrounding IUC has only just started.



4.3 ON-ROAD EMISSION TESTING FOR IN-USE CONFORMITY

4.3.1 From the USA study tour

On-road or roadside measurement systems could be used as a screening tool for in-use conformity.

That is, these systems could be used to identify possible problem engines (or engine families). These engines

could then be tested, using a chassis dynamometer and finally on an engine dynamometer for full in-use con-

formity checking. The latter testing would be rather expensive and a system would need to be devised that

did not inconvenience vehicle operators. One manufacturer suggested that it might be more appropriate to

simply to check that the after-treatment device is in place and is working.

The Consent Decrees require the manufacturers to contribute towards the development of an on-road

measurement system. This system is known as MEMS (Mobile Emissions Measurement System) and is be-

ing developed at West Virginia University. The EPA is also developing two alternative systems, called

Rover (Real time On-road Vehicle Emission Reporter) and Spot. The latter is also known as PEMS (Portable

Emissions Measurement System), and has been developed primarily for developing emission factors for off-

road vehicles. One of the main difficulties has been measuring the exhaust flow rate. Ford Motor Company

has also developed a system for gasoline vehicles know as Preview (see 4.3.3.1).

4.3.2 Manufacturers’ vision on on-road measurement systems

Cummins believes that MEMS is better than Rover, but are waiting for EPA’s official response. None

of the three manufacturers have yet tested MEMS. Most of the testing undertaken by the University of West

Virginia has used a Mack engine.

The HD engine manufactures believe that the EPA will use on-road measurement as a screening tool,

with further chassis and engine dynamometer tests required to confirm non-conformity, at least initially.

Only when on-road measurement has been shown to correlate well with engine dynamometer tests can it be

used as a conformity enforcement tool. The EPA confirmed that this would require additional rulemaking

(and a four year lead time). Therefore, it could not come into force until 2011 at the earliest.

As the emission levels decline from 2007, it will become increasingly difficult to undertake on-road

measurements. The ‘noise’ is likely to be of the same order of magnitude as the measurements. Comparing

on-road emission measurements with the ‘Not to Exceed’ limits will also require a robust method of convert-

ing gram/second into g/brake horsepower hour for measurements averaged over a minimum of 30 seconds.

The Consent Decrees require on-road measurement of torque with increasing accuracy.



In Caterpillar’s view the development of a sufficiently accurate on-road measurement device is a long

way off. Cummins believe that it is not really on the political agenda yet and that an on-road test of the after-

treatment device will probably be sufficient.

4.3.3 Review of known on-road systems

A list has been prepared of the mobile emission measurement systems (measuring and acquiring the

mass of HC, CO, CO2 and NOx, PM optional), that are known. These systems were developed by automotive

manufacturers, manufacturers of measurement equipment, universities or research institutes, and will be re-

viewed.

It is not obvious to compare the different on-board emission measurement systems on common specifi-

cations, as this is not a standard technique. Every author describes his system in his own way together with

‘in-house’ specifications. Furthermore, definitions can vary between authors, for example accuracy can be

given as a typical accuracy or as an average figure, etc. Nevertheless, in the description of the systems an

effort is made to discuss them under eight parameters:

Name Acronym and/or full name of the system

Use Typical use of the system, e.g. for diesel fuelled vehicles, especially for

IUC testing, etc.

Principle Measurement principle, e.g. on raw or diluted exhaust gas, bag collection or

continuous measurement, dynamic measurements or not

Methodology How the mass emissions results are calculated from the measurements, e.g.

emission concentration measurements coupled with exhaust gas flow rate

from direct determination

Emissions covered The measured exhaust emission components are detailed

Apparatus Analyser make and type, etc.

Inaccuracy Measurement results on-road are referred to measurement results on a chas-

sis dynamometer.

Weight/size Portability of the system

If no information is available on a parameter the corresponding line is left blank.



4.3.3.1 Systems developed by automotive manufacturers:

Caterpillar

A portable bag collection system was developed by Caterpillar to quantify fuel specific NOx emis-

sion levels for in-use diesel engines in 1982 [11].

Name

Use In-use emission measurements on HD diesel engines

Principle Raw exhaust in bag, with water removal before the bag.

No dynamic measurements

Methodology Concentration measurement, fuel specific emissions

Emissions covered NOx

Apparatus Bag collection

Inaccuracy 10% on a concentration base

Weight/size ‘suitcase’ size

Ford

Ford started to develop an on-road emission measurement system in the early nineties. This resulted

in a system for measuring gasoline vehicles [11].

Name OBE

On-Board Emissions

Use emission measurements on gasoline LD vehicle for simultaneous compari-

son to remote sensing of exhaust

Principle continuous diluted exhaust measurement

Methodology

Emissions covered CO2, CO, HC, NOx

Apparatus FTIR plus dilution tunnel

Inaccuracy < 10%

Weight/size

Further developments of this system resulted in Preview [14]. The Ford Preview system (for measur-

ing gasoline vehicles) appears to be well developed. It can measure emissions down to the SULEV levels

with a good correlation with chassis dynamometer measurements. This system has largely been developed to

reduce engine optimisation costs, as it allows operability and emissions to be calibrated together, rather than



calibrating for operability and then going into the laboratory for an emissions test. It is likely that Sensors

Inc, which has been involved in the development of Preview, will market the product, which might also in-

clude a diesel version (see 4.3.3.2).

Name Preview

Portable Real-time Emission Vehicular Integrated Engineering Workstation

Use In-use emission measurements on LD gasoline vehicles

Principle Continuous raw exhaust measurement

Methodology Concentration measurements coupled with exhaust gas flow rate derived

from engine parameters

Emissions covered CO2 CO NO HC

Apparatus Co-development with Sensors Inc.

Inaccuracy <4% <4% <4% <12%


Volkswagen

The development of this system was started 13 years ago. The deviations from measurements on a

CVS system appeared to be less than 10% [15, 16].

Name

Use in-use emission measurements on gasoline LD vehicles

Principle continuous raw exhaust measurement

Methodology concentration measurements coupled with exhaust gas flow rate derived

from fuel consumption and air/fuel ratio measurement

Emissions covered CO2 CO HC NOx

Apparatus Horiba Mexa 1440 NDIR Horiba Mexa

1440 CLD

Inaccuracy <10% <10% <10% <10%

Weight/size Filling car boot

Another system was also developed by Volkswagen in collaboration with IAV. This system is

nowadays mainly used for correlating chassis dynamometers on emission (CVS) measurements. Vito visited



Volkswagen and had the system demonstrated. No further developments of the system were planned. It was

satisfactory in its actual status (specifications were handed to Vito).

Name MOBGAS

Mobile onboard gas analyser

Use At present : for emission correlation engineering

In future : in-use emission measurements on gasoline LD vehicles


Methodology Concentration measurements coupled with exhaust gas flow rate derived

from fuel consumption and air/fuel ratio measurement

Emissions covered CO2 CO NO HC

Apparatus ABB Hartmann & Braun

Advance Optima URAS 14

Testa FID

Type 2001T

Inaccuracy <5% < 10% < 10% < 10%

Weight/size filling car boot



General Motors

The system was patterned on EPA’s ROVER device. Concentrations of emissions measured with

Snap On 5-gas analyser [11].

Name

Use In-use emission measurements on a 1989 gasoline LD vehicle in city and on

highway


Methodology concentration measurements coupled with exhaust flow rates that were de-

rived from intake air flow rates

Emissions covered CO2

CO HC NO

Apparatus Horiba

Mexa 311GE

Horiba

Mexa 324GE

Siemens

Ultramat 22P

Draeger (in-car

ambient CO)

Horiba

Mexa 311GE

Horiba

Mexa 324GE

Siemens

Ultramat 22P

Siemens

Inaccuracy

Weight/size 180 kg, filling car boot



Honda

This system is based on FTIR analyser (Nicolet Protégé 460) for measuring ULEV. It is in use at

Honda for development of emission control devices [11, 18, 19].

Name

Use In-use emission measurements on ULEV and below LD gasoline vehicles

Principle Continuous raw exhaust measurement, water removal over Nafion mem-

brane

Methodology concentration measurements

Emissions covered CO, NMHC and NOx

Apparatus Fourier Transform Infrared (FTIR) analyser Nicolet Protégé 460

Inaccuracy

Weight/size

4.3.3.2 Systems developed by manufacturers of measurement equipment:

Horiba

Horiba developed a real-time on-board measurement system for measuring the mass emission of

NOx. The influence of climatic parameters (ambient temperature and humidity) was also measured [11, 19].

Name

Use In-use emission measurements on diesel vehicles

Principle Direct continuous raw exhaust measurement

Methodology Concentration measurements coupled with exhaust flow derived from sen-

sors

Emissions covered NOx

Apparatus NOx NGK sensor, a Universal Exhaust Gas Oxygen (UEGO) sensor and an intake air flow Karman Vortex meter

Inaccuracy <4% for NOx

Weight/size very small, as all based on sensors



Clean Air Technologies

The portable on-board mobile emissions monitor OEM2100 is also being used by the North Carolina

State University for measuring on-board emissions [20, 21]

Name OEM 2100

Portable Onboard Mobile Emissions Monitor

Use in-use emission measurements on gasoline LD vehicles


Methodology concentration measurements coupled with exhaust gas flow rate derived

from engine parameters

Emissions covered CO2, CO, HC, NOx, O2

Apparatus five gas analyser

Inaccuracy


Sensors Inc.

A system for measuring in-use emissions was developed by Sensors Inc. Extensive information was

available from Sensors on the system. Information is also available on the website [22]. Sensors developed a

gasoline and a diesel measuring system.

Name Semtech-D

Use in-use emission measurements on diesel and gasoline vehicles, aimed at

IUC measurements giving brake specific emissions for HD vehicles


Methodology concentration measurements coupled with exhaust gas flow rate from direct

determination

Emissions covered CO2, CO, HC, NO, NO2, O2

Apparatus heated FID (HC); NDIR analyser (CO2, CO); NDUV analyser (NO, NO2)

Inaccuracy




4.3.3.3 Systems developed by universities:

West Virginia University

The Mobile Emissions Measurement System (MEMS) is being further developed as a consequence

of the ‘consent decree’ phase I [11, 28]. The engine manufacturers that have to comply with the consent de-

cree contracted West Virginia University to develop the system.

Name MEMS

Mobile Emission Measurement System

Use in-use emission measurements on diesel vehicles, aimed at IUC measure-

ments giving brake specific emissions for HD vehicles



determination

Emissions covered CO2 NOx

Apparatus Horiba BE 140 NDIR Horiba Mexa 120 ZrO2 sensor

Annubar with differential pressure transducer (Validyne P365) and absolute

pressure transducer (Omega PX176 or PX203) for exhaust flow rate

Inaccuracy <5% <5%


University of Pittsburgh

The system was developed as an on-board emission measurement system for I/M applications [11].

Name

Use in-use emission measurements on natural gas vans


Methodology concentration measurements coupled with OBD-II engine data

Emissions covered CO2, CO, HC, NO, O2

Apparatus OTC SPX RG240 five gas analyser

Inaccuracy




Nescaum

This system was developed for a study by the North East States for Coordinated Air Use Manage-

ment [11].

Name

Use in-use emission measurements on diesel off-road construction vehicles ex-

amining different emission control technologies

Principle continuous and bag diluted exhaust measurement, PM collection on filter

Methodology Emission measurements on a mini-dilution tunnel

Emissions covered CO2, CO, HC, NO and PM

Apparatus MPSI five gas analyser

Inaccuracy 10-30% spread for CO, HC and NO

Weight/size



4.3.3.4 Systems developed by research institutes:

EPA

ROVER, the patented equipment was based on this system.

Name Rover

Real-time On-road Vehicle exhaust gas modular flow meter and Emissions

Reporting system

Use in-use emission measurements on LD and HD gasoline and diesel vehicles,

aimed at IUC measurements giving brake specific emissions for HD vehi-

cles



determination

Emissions covered CO2, CO, HC, NO, O2

Apparatus Snap-On MT3505 multi gas analyser

Annubar with differential pressure sensor for exhaust flow rate

Inaccuracy


South West Research Institute

Name

Use emission measurements on diesel busses through cycles on the parked vehi-

cle performed against the automatic transmission

Principle raw exhaust in bag, mini-dilution tunnel for PM, no dynamic measurements

Methodology concentration measurement

Emissions covered CO2, CO, NOx, O2, PM

Apparatus Enerac 2000E, measuring on the collected bag

Inaccuracy 5% on a concentration base




Vito

Vito, the Flemish Institute for Technological Research, developed a system for the on-road meas-

urement of emissions at the beginning of the nineties. This system was used in several projects [23].

Name VOEM

Vito’s On-the-road Emission and energy Measurement system

Use commercially offered in-use emission measurement service on gasoline,

diesel, biodiesel, natural gas and some LPG LD and HD vehicles; separate

module for hybrid vehicles

Principle Continuous diluted exhaust measurement

Methodology Gaseous concentration measurements or PM mass rate coupled with exhaust

gas flow derived from fuel consumption and lambda; automated data-

treatment

Emissions covered CO2 CO HC NOx CH4 PM

Apparatus Rosemount

Binos 100/1000 NDIR

JUM

FID 3-100

Rose-

mount

CLD

951A

Rose-

mount

Binos

1001

NDIR

R&P

TEOM

1105 cou-

pled with

a micro

dilution

tunnel

Horiba

MDT-905

Inaccuracy < 10% <25%




For measuring low emission vehicles, the VOEM system was redesigned, resulting in the VOEMlow

system [24].

Name VOEMLow

Vito’s On-the-road Emission and energy Measurement system for Low

emitting vehicles

Use Commercially offered in-use emission measurement as service or as prod-

uct; for gasoline, diesel, biodiesel, natural gas and some LPG LD and HD

low emitting vehicles; separate module for hybrid vehicles


Methodology Gaseous concentration measurements coupled with exhaust gas flow de-

rived from fuel consumption and lambda; automated data-treatment

Emissions covered CO2 CO HC NOx

Apparatus Rosemount NGA 2000

NDIR

Rosemount

NGA 2000

FID

Rosemount

NGA 2000

CLD

Inaccuracy <10% <10% <10% <10%


Warren Spring Lab (70’s)

No current information was available about this system.

Name mini Constant Volume Sampling (CVS) system

Use In-use emission measurements on gasoline and diesel LD and HD vehicles

Principle dilute exhaust in bag, no dynamic measurements

Methodology CVS on a proportional exhaust sample

Emissions covered CO2, CO, HC, NOx, PM

Apparatus own design of mini-CVS including exhaust beam-splitter

Inaccuracy <10% for all emissions




FZ Jülich

FZ Jülich, the Research Institute Jülich, developed a system for on-board emission measurements

including speciated hydrocarbons in 2000. A first paper on the system is scheduled for 2002.

Name

Use in-use emission measurements on gasoline LD vehicles; measurement of

speciated hydrocarbons

Principle Continuous diluted proportional exhaust measurement; bag analysis for spe-

ciated hydrocarbons

Methodology Gaseous concentration measurements coupled with exhaust gas flow de-

rived from fuel consumption

Emissions covered CO2 CO HC NOx O2 Speciated

HC

Apparatus TE 48C H&B FID TE 42C Gas

Chroma-

tography

H&B Ad-

vance Op-

tima

H&B Ad-

vance

Optima

H&B Ad-

vance Op-

tima

H&B Ad-

vance Op-

tima

Inaccuracy




4.3.3.5 OBM

On-Board Monitoring (OBM), i.e. the direct measurement of emissions on-board of each vehicle,

would be an ideal supplement to OBD. It is largely dependent on the availability of suitable sensors. These

are in the early stages of development. The one known effort in this area is presented is the same way as the

on-board measurements.

Wissenschaftliche Werkstatt für Umweltmesstechnik GmbH

Name OBM

On-Board Monitoring

Use to be OEM installed on every vehicle on the exhaust pipe


Methodology concentration measurements, in future linked to vehicle OBD system

Emissions covered CO2, HC, NO

Apparatus special design, very compact

Inaccuracy

Weight/size 120 x 300 x 80 mm

OBM development is in its infancy as the needed sensors will require many more years of development. The

time frame is not known but generally estimated at about ten years. The ongoing development presented uses

available IR techniques instead of sensors. It is uncertain whether this technique is robust enough with re-

spect to shocks, vibrations, etc. for implementation in HD vehicles. This development still needs a few years

at the minimum.

4.3.4 Proposed equipment EPA

The ‘Environmental Protection Agency’ (EPA) has called for a ‘Cooperative research and develop-

ment agreement’ (CRADA) for the development of an ‘on-board exhaust emission measurement system’.

The system is described in the ‘statement of work’ added to the call published in the CBD on 13th of June

2001. The requirements that apply for this system give us an idea of how the EPA thinks of in-use confor-

mity testing on-road and verifying the not-to-exceed limits (NTE). In the following table 4 the system is de-

scribed (more details are given in annex 9.2).



Table 4

On-Board exhaust emission measurement system

Basic system

Core product

Measuring: NOx an CO2 concentrations, fuel economy,

intake and exhaust flow, temperatures, pres-

sures, relative humidity, engine speed, engine

torque, CAN/ECM signals, GPS-signal

Accuracy: at least 10%

Weight max. 25 kg

Size hand-carried toolbox

Modules

Gasoline SI: measuring CO, HC, λ

Rugged enclosure: with unattended operation for 1 week

Additional

Measuring: THC, NMHC, PM, air toxins, direct torque

The objectives to be realised with this system (based on ROVER, Real-time On-road Vehicle exhaust gas

modular flow meter and Emissions Reporting system, patented by EPA) are the measurement of low emis-

sions in a rough environment by non-specialised personnel. With the system it will be possible to collect

more real-life data, so the effects of the emission requirements can be verified.

Due to the fact that the system has to be developed within 6 months, it may be assumed that the system is

needed in a very short time.

Some remarks

The specifications set out by the EPA for a commercially viable on-board exhaust emission measurement

system in its call for a CRADA are very demanding but well studied and realistic. The six months timeframe

for the CRADA is optimistic. At the time of finalising this report (May 2002) the EPA instead of doing a

CRADA proceeded to issue a Request For Procurement (RFP) to purchase commercial units according to

specifications they described in the RFP.



As measuring on-board is a new area some extra specifications are necessary. Whereas laboratory

grade equipment is installed and used in a protected environment, on-board systems work under harsh condi-

tions and are subjected to shocks, vibrations, dust, temperature fluctuations, direct sunshine, etc. This occurs

not only during the measurements but also during transport. To guarantee the accuracy specifications under

these conditions extra testing is necessary. A real-life approach is possible measuring calibration gasses on-

board in the vehicle under test. This is most realistic as to the testing conditions and could serve as an on-

vehicle check. Another approach more suited to setting specifications can be under controlled conditions as

to frequencies and amplitudes on an excitation table. The environmental conditions can be varied too, par-

ticularly temperature.

The accuracy specification of at least 10% should be better detailed. Usually CVS systems are cho-

sen as reference in tests with simultaneous on-board system measurements. IUC checking on US 2007 com-

pliant vehicles deals with measuring concentrations of just a few ppm. For comparison: a CVS system, even

enhanced, or bag mini diluter (BMD) will be inaccurate to at least 10% given SULEV NMHC LD emission

levels [25]. So another reference is needed traceable to SI unit definitions. A possibility here is an enhanced

exhaust gas simulator [26] delivering known quantities of emission products.

4.3.5 Review of possible on-road test procedures

If future IUC emission regulation requires on-road measurement, then test procedures will need to be

developed. These should cover aspects such as test conditions, test cycles, test infrastructure, test emission

limits, and they should provide a link to the certification and durability regulations. Note that on-road testing

implies that the measurements are carried out on the vehicle level and outdoors.

4.3.5.1 Test conditions

The conditions for executing the test need to specify what climatologic and vehicle specific condi-

tions have to be met. Also boundaries to altitude and road gradient have to be set.

As to the climatologic conditions allowable ranges need to be defined for air temperature, atmos-

pheric pressure and relative humidity. As long as the vehicle stays within these boundaries the test is valid.

An example of such ranges can be found in the USA NTE approach (see section 4.2.1.1). The ranges should

be relatively wide to account for common climatologic conditions. On the other hand extreme conditions



should be excluded. However, as common conditions vary considerably in the EU from North to South, it

may be advisable to define an extended range upon the normal one. If the vehicle is in the extended part

higher emission limits should be set, for example by the use of a multiplier on the limits of the normal range.

Furthermore, it has to be decided if precipitation - rain or snow fall - is allowed and if so to what ex-

tent. Loss of grip on the road or extra wheel slip resulting from precipitation will influence the test results.

The more demanding the test cycles are, the higher the influence. It might be wise to allow no precipitation

and to test only on a dry road. This will however limit the amount of test days in a year. Moreover, this

amount is EU country dependent presenting a situation where countries with little precipitation will have

more ‘usable’ days.

Last but not least testing in fog should be excluded. Apart from being unsafe it can influence emis-

sions to an unknown extent. The allowable range set on relative humidity will not amount up to 100% and

so will exclude fog being a typical 100% relative humidity condition.

In general, all test conditions, potentially influencing the test result, should be evaluated in practice

through dedicated tests. The amount of influence will be determined and the way how to cope with it should

be given.

4.3.5.2 Vehicle conditions

As to the specific conditions of the vehicle, such parameters as load, tyre pressure, service (history),

etc. need to be defined. As to the vehicle load, any allowable load should be OK. If for example a high load

is used, the engine will be in another operating point. As long as it stays in the control area, the test is valid.

Vehicle conditions can have a major influence on the test results. In any case it should be ascertained that

the vehicle is in-use representative for its type.

The boundary conditions for altitude and road gradient apply to all types of test cycles.

4.3.5.3 Test cycles

Next the type of test cycle has to be agreed upon. The candidates include: no test cycle, fully speci-

fied driving cycle, target speed cycle and stationary mode cycle.

The ‘no test cycle’ option equals normal driving on typical public roads by the usual driver, just as

the vehicle would do in its everyday use. It is the way of testing thought of in the USA under the IUC NTE

approach. A clear advantage is the real-life content. The disadvantage is the lack of reproducibility. Every

test will be unique and not repeatable, and thus results of different vehicles cannot be compared.



The opposite of the ‘no test cycle’ is the fully specified driving cycle. This one can be compared in

its definition to dynamometer cycles: a fixed speed versus time curve including gear shift points is pre-

scribed. Consequently a driver’s aid has to be installed in the vehicle similar to the one with the chassis dy-

namometer. The driver has to follow the speed-time curve by keeping the actual vehicle speed at the curve

within agreed limits. An accurate speed determination by dedicated sensors fed in real-time into the driver’s

aid is necessary. This cycle has the advantage of its reproducibility except for the climatologic conditions.

Disadvantage is the use of the same cycle for widely varying kinds of HD vehicles.

The target speed cycle tries to include aspects from the “no cycle” and the fully specified cycle.

Target speeds are set and the vehicle accelerates to these speeds according to its power. So part of the test is

fixed and part is vehicle specific. The test is distance based. A driver’s aid is also needed with the extra fea-

tures of on-line real-time ‘distance driven’ calculation and ‘rest of cycle’ determination. The target speed

cycle is best looked upon as a compromise.

A stationary mode ‘cycle’ consists of steady state parts (fixed vehicle speeds). Accelerations and de-

celerations are not included. Advantages are the test simplicity and the resemblance to the ESC test. A clear

drawback is the missing real-life aspect.

The choice of test cycle will also depend on other items in the test procedure such as the test infra-

structure and the way to impose limits (see next paragraphs).

4.3.5.4 Test infrastructure

The test infrastructure could be just the public roads, or a private proving ground or even a chassis

dynamometer. Public roads are ideal for the “no test cycle” option, i.e. real-life driving. This presents a low

cost solution at a maximum in availability. The other types of test cycles need a private proving ground as

they can obviously not be realised during normal driving. The cost of this solution is higher and the avail-

ability of proving ground is lower, both geographically and time wise (proving grounds can be extensively

used by different customers). This higher cost is the price that is paid for more reproducible testing. Also a

chassis dynamometer could be used. Except for the “no test cycle” option all other cycles can be run on a

dynamometer using the existing infrastructure with a far better control on climatologic conditions (especially

temperature and to a lesser extent relative humidity) and without the need for an on-road measuring system.

However, only a few HD chassis dynamometers are available throughout the EU and they are very expen-

sive.



4.3.5.5 Emission limits

Different ways can be thought of to impose emission limits, for example NTE limits, limits on the

integrated emission over the entire test cycle or idem per fragment of the test cycle.

NTE limits (see section 4.2.1.1) are specifically designed with the aim of possible IUC use. They can be ap-

plied to all test cycles except the stationary mode one. They are the only feasible ones for the “no-test cycle”

option.

A set of limits on the integrated emissions over the entire test cycle is the common, more rigid ap-

proach out of certification testing. It reveals few details on the short term transient vehicle emissions, as

these are spread out over the entire cycle.

The same concept but on a per fragment base of the cycle is a solution in terms of details of emission

behaviour in between the two earlier mentioned ones. Fragments could be defined as accelerations, decelera-

tions and steady-state driving.

4.3.5.6 Certification and durability regulations

Finally the on-road test procedure should provide a link to the certification and durability regulations

to be ‘in-use compliant’ with these. This can be achieved by applying part of the on-road procedure to the

certification and durability testing. For instance NTE limits should be enforced in certification and durability

testing alongside the existing limits. Of course, there is also a link between IUC and durability testing in that

IUC requirements continue until the vehicle drops out of durability requirements either by age or distance

driven.

4.3.5.7 Conclusion

It can be concluded that there are many possibilities to on-road testing depending on what approach

to IUC will be taken. This novel field should be further researched and discussed by the parties involved and

certainly with the engine and vehicle manufacturers.

4.3.6 Review of heavy-duty in-use conformity systems

The mechanism for enforcement of in-use conformity testing to heavy-duty vehicles should follow

that laid down for light-duty and small commercial vehicles and referenced in the type-approval framework



Directive (Directive 70/156/EEC, as amended). No further discussion is made here. The Commission has

still to decide on the technical scope of the in-use conformity testing scheme for heavy-duty vehicles.

4.3.7 Financial implications

This section is intended to provide preliminary cost estimations for on-road IUC testing. This cost

comprises of the cost for organising the IUC testing according to the regulations and the cost for the actual

emission testing. Cost figures are difficult to obtain so the authors based themselves on their experience too.

4.3.7.1 USA

The global cost for testing a HD gasoline vehicle under the USA CAP2000 IUC regulations is esti-

mated at 4,600 USD per test [27]. On a per sold vehicle base this roughly amounts up to 1 USD if per engine

family 10 tests were to be executed.

The cost for testing a HD diesel vehicle on-road using a measurement system similar to the one

asked for by the EPA in the call for a CRADA (Cooperative Research And Development Agreement) (see

section 4.3.1) is 2,500 USD per test. The test consists of two hours preparation and one to two hours of

measurements [9]. The cost for organising the IUC testing on a per vehicle base has to be added.

4.3.7.2 Europe

From offering and carrying out on-road measurements on HD vehicles using a research grade system

Vito arrives at a cost per test of 8,000 EUR. This includes four hours of testing in a three days period. Also

here the cost for organising IUC has to be added.

For comparison the authors estimate from experience the cost for executing a steady state to semi

dynamic test on a stationary chassis dynamometer at 8,000 EUR per test. The cost figure for dynamic testing

on a dynamic chassis dynamometer is not known but exceeds 8,000 EUR per test. Finally, testing the engine

on a dynamic engine dynamometer might exceed 25,000 EUR per test.

Without knowing the exact costs of organising IUC on-road testing, of carrying out the test method

of choice and of the number of tests/vehicles, it is difficult to calculate a global cost.



4.3.8 Potential of on-road system use for in-use conformity testing

The potential of using on-road systems for IUC can be evaluated both theoretically and practically.

Also the potential phase-in in time is given some thought.

4.3.8.1 In theory

In theory the potential of on-road (on-board) systems for verifying IUC of HD vehicles is very high.

They can use the NTE concept during real world driving under real-life conditions on public roads. This is

believed to be the best approach for ensuring that vehicle in-use emissions are under control and remain as

such throughout the useful life of the vehicle. It also provides the best way of ensuring that manufacturers do

not employ irrational control strategies. Furthermore, on-road testing is as cost effective or possibly better

(see section 4.2.2.8) as its alternatives such as chassis or engine dynamometer testing. Considerable knowl-

edge will be gained about real-life emissions, though these data are less suitable for generating representative

emission factors and bottom-up emission models.

4.3.8.2 In practice

At present no on-road systems are available that match the specifications set out by the EPA in its

call for a Cooperative Research And Development Agreement (CRADA) on a commercially viable on-road

system (see section 4.3.1). In particular the size and accuracy specifications are difficult to match. Either the

system size is small enough but the accuracy is/will be insufficient for Euro 5/US2007, or vice versa due to

the use of laboratory grade emission analysers that are more accurate but also larger in size.

The demand for brake specific emission figures necessitates the retrieval of torque from the engine’s

management system. The accuracy of the emission determination is directly dependent on the accuracy of

this torque which is at present an estimate with an average error of 5-10%. In future torque based engine

management systems will supply torque figures with a far better accuracy and resolution (to a few Nm).

It should be noted that on-road measurement methodologies are intrinsically incorrect. Different pa-

rameters such as emission concentrations and exhaust gas flows need to be combined in a time aligned fash-

ion to produce mass emissions. This synchronisation is never perfect. Furthermore, time response functions

of, for example, analysers affect the accuracy of the time alignment of the signal. In fact the inaccuracies in-

troduced by the methodology can be the determining ones for the entire on-road system

With USA in-use conformity NTE limits at only 1.5 times the FTP certification limits, on-road sys-

tems need to offer the same accuracy as laboratory grade systems in a suitcase package. With the US2007



emission limits, exhaust emission concentrations are lower than a few ppm. It is quite a challenge to realise

such a system and one that might well be years away. Considerable technology forced R&D will be neces-

sary.

Once suitable on-road systems exist their use will, besides IUC-testing, probably also be found in

development programmes.

4.3.8.3 Phasing in of on-road testing for in-use conformity

Given on the one hand the amount of research and development still necessary and on the other hand

the estimated ‘ten plus’ years timeframe for IUC emission regulation to include on-road testing, a phase-in of

this technique will probably occur.

At first on-road systems will serve the determination of emission factors, the evaluation and/or com-

parison of different technologies under real-life driving conditions, etc. In this phase the field experience

gained will serve as feedback for the development of better systems.

Subsequently these systems can be used as screening tools for IUC i.e. those vehicles that do not

pass the NTE limits need to be checked by the manufacturer on a chassis or engine dynamometer. The latter

test result is final. The better the on-road systems perform, the better the correlation between on-road and

dynamometer testing.

Finally, when on-road systems have shown their potential as screening tools and when on-road IUC

is integrated in the emission regulation, on-road systems could serve as enforcement tools, maybe even with-

out the need for additional dynamometer measurements. Also, those vehicles possibly equipped with on-

board monitoring (OBM) can be evaluated for the accuracy of their OBM measurement system.

If the legislator wants to include on-road IUC in the regulations before on-road systems can serve as

enforcement tools he can choose to employ the on-road systems as screening tools i.e. using dynamometer

measurements as a follow-up test should the vehicle fail to pass the on-road test (see above). Alternatively he

can enforce dynamometer measurements directly without the need for on-road measurements and meanwhile

evaluate the on-road measurement systems (in pilot projects) until these are ready to serve as enforcement

tools.



4.4 APPLICABILITY OF IN-USE CONFORMITY FOR FUTURE TECHNOLOGY

After-treatment devices and their control strategies are very sensitive to transient behaviour of the en-

gine, and in some cases (e.g. a particulate filter) a shift in time is introduced between the moment emissions

are produced in the engine and when they are released from the exhaust. The influence these effects have on

an IUC test result cannot be neglected.

It might well be possible that during regeneration of the filter the NTE limits are exceeded for some

periods whereas in between regenerations emissions are well below the limits. A possible solution could be

presented through the OBD or OBM link of the emission measurement system. As long as regeneration oc-

curs the OBD system has to flag this. The measurement system could then allow for the NTE limits to be

exceeded. A higher limit, for example two times the NTE, could be set for the duration of the regeneration

phase. Later on the average value for the entire cycle can be calculated. All excess emissions to that average

value from during the regeneration phase could, for example be evenly distributed over the rest of the cycle.

The then recalculated NTE results have to meet the original NTE limits over the entire cycle. The above

method can only be applied correctly if the time between regenerations is known. Only then a correct aver-

age value can be calculated. Note also that NOx absorbers collect emissions and discontinuously release

those from the absorber.

It can be concluded that all future concepts for emission control should be checked for their IUC com-

patibility. Also, if emission control techniques are employed that need regeneration phases, etc., it has to be

proven that the latter were included in the IUC testing.



5 CONCLUSIONS

5.1 MOMENTARILY NO REGULATIONS

At present there is no heavy-duty in-use conformity regulation in place, either in the USA, or in the

EU. Looking at the upcoming Euro 4 regulation, in the EU a slightly adapted LD Euro 3 IUC system may be

proposed, in terms of the mechanism for enforcement. The technical details have still to be finalised. In the

USA no IUC regulation is incorporated in the 2004 and 2007 sections of the Code of Federal Regulation

(CFR86).

An assessment of possible laboratory and on-road test procedures for IUC revealed that the best choice

depends on the particular aims that the legislator has set for his IUC programme. Generally, laboratory tests

offer better compliance with certification legislation, better research of maintenance effects on emissions and

better accuracy as well as reproducibility. On-road testing yields better cycle bypassing resistance and equal

to possibly better cost-effectiveness (to be confirmed). OBD is not believed to be able to replace IUC. For

OBM this is unclear and will need further evaluation as this technique develops.

The manufacturers state that on-board diagnostics (OBD) and future on-board monitoring (OBM) will

make in-use compliance superfluous. In case of IUC they disagree on whether testing should be done on-

road or on chassis or engine dynamometer. However, when vehicles are equipped with OBD/OBM, it has to

be verified whether these systems are working correctly. So the IUC procedure will consist of testing these

systems to their specifications.

5.2 DIFFERENCES BETWEEN USA AND EU

In the US NTE limits are incorporated as part of the engine certification procedure. This could open

the way for a future IUC based on these NTE limits. The actual IUC testing could be performed on (engine

or chassis) dynamometer or on-road. For on-road tests the NTE limits are well suited, as this means that the

vehicle can be operated normally in traffic (instead of following a prescribed speed cycle).

The USA IUC approach when applied in the EU might need adaptations relating to the differences in

vehicle use between the USA and the EU. The NTE concept itself is believed to be universally applicable.

However, the definition of the NTE zone and the carved out areas, the engine classification and the (test)

methodology could be specific for the EU situation. In particular the carve-out below the 30% maximum

power curve needs attention. In the EU HD engines mounted in on-road vehicles operate for a considerable

time underneath this curve. This is especially true for MHDDE and LHDDE. The data gathered in the study



on the WHHD cycle should be examined to help propose a new carve-out at a lower then 30% maximum

power curve. With harmonisation in mind though, the methodology should be as alike as possible in as many

aspects as feasible.

It might be advisable to extend the certification testing to include NTE testing along the WHHD cycle.

This yields a link between a real-life based certification cycle and in-use conformity testing as NTE testing is

a factor common to both. The path along the WHHD cycle presents a long term approach. It might well take

until 2012-2015 before a concept like the WHHD cycle is incorporated in the USA, Japanese and EU emis-

sion legislation.

5.3 NTE APPROACH LOOKS PROMISING

The NTE limit definition enforced on a HD vehicle looks suitable for IUC. Within relatively wide in-

tervals for environmental parameters such as temperature, relative humidity, etc., the vehicle has to comply

with the NTE limits for the defined NTE control area underneath the max. torque-rpm curve of the engine.

As the NTE limits are only 1.5 times the FTP certification limits, some areas underneath the torque-rpm

curve are carved out i.e. those areas with high brake specific emissions that are believed to be less frequented

by the vehicle.

However, in phase II of the work carried out by West Virginia University under the Consent Decrees,

on-road testing revealed that remaining for 30 seconds within the NTE zone can be quite difficult. The re-

sulting low NTE availability poses a problem as many measurements from within the NTE area have to be

rejected along with those from outside the NTE area. The question arises if in this way all real-life emissions

are sufficiently well ‘weight reflected’ in the NTE test results.

All future concepts for emission control should be checked for their IUC compatibility. Also, if emis-

sion control techniques are employed that need regeneration phases, etc., it has to be proven that the latter

were included in the IUC testing.

More field experience with the NTE approach will show how well the concept works and where im-

provements and further research might be necessary. In particular the influence of varying test conditions

should be evaluated in order to define allowable intervals. Still it is believed that, given a good approach, the

engine is tested under a wide variety of in-use conditions, thus ensuring that the in-use emissions are under

control.



5.4 ON-ROAD MEASURING NEEDS FURTHER INVESTIGATION

If future IUC emission requires on-board on-road measurements, which is a completely new way of

testing, then specific test procedures will need to be developed. These should cover aspects such as test con-

ditions, test cycles, test infrastructure, test emission limits, and they should provide a link to the certification

and durability regulations.

Without knowing the exact costs of organising IUC on-road testing, of carrying out the test method of

choice, and of the number of tests/vehicles, it is difficult to calculate a global cost.

In theory the potential of on-road (on-board) systems for verifying IUC of HD vehicles is very high.

They use the NTE concept during real world driving under real-life conditions on public roads. This is be-

lieved to be the best approach for ensuring that vehicle in-use emissions are under control and remain as such

throughout the useful life of the vehicle. It also provides the best way of ensuring that manufacturers do not

employ irrational control strategies. Furthermore, on-road testing is as cost effective or possibly better (to be

confirmed) as its alternatives such as chassis or engine dynamometer testing. Considerable knowledge will

be gained about real-life emissions too, though these data are less suitable for generating emission factors

and bottom-up emission models.

However, at present no on-road systems are available that match the demanding but well thought of

specifications set out by the EPA in its call for a ‘Cooperative Research And Development Agreement

(CRADA)’ on a commercially viable on-road system. In particular the size and accuracy specifications are

difficult to match. Either the system size is small enough but the accuracy is/will be insufficient for Euro

5/US2007, or vice versa. With USA IUC NTE limits at only 1.5 times the FTP certification limits, on-road

systems need to offer the same accuracy as laboratory grade systems in a suitcase package. At the US2007

emission limits exhaust emission concentrations are lower than a few ppm. It is quite a challenge to realise

such a system and one that might well be years away. Considerable technology driven research will be nec-

essary.

The demand for brake specific emission figures necessitates the retrieval of torque from the engine’s

management system. The accuracy of the emission determination is directly dependent on the accuracy of

this torque which is at present an estimate with an average error of 5-10%. In future torque based engine

management systems will supply torque figures with a far better accuracy and resolution (to a few Nm).

Given on the one hand the amount of R&D still necessary and on the other hand the estimated ‘ten

plus’ years timeframe for IUC emission regulation to include on-road testing, a phase-in of this technique

will probably occur. At first on-road systems will serve the determination of real life emission data, the

evaluation and/or comparison of different technologies under real-life driving conditions, etc. Subsequently

these systems can be used as screening tools for IUC, i.e. those vehicles that do not pass the NTE limits need



to be checked on a chassis or engine dynamometer. Finally, when on-road systems have shown their poten-

tial as screening tools and when on-road IUC is integrated in the emission regulation, on-road systems may

serve as enforcement tools without the need for additional dynamometer measurements.

If the legislator wants to include on-road IUC in the regulations before on-road systems can serve as

enforcement tools he can choose to employ the on-road systems as screening tools i.e. using dynamometer

measurements as a follow-up test should the vehicle fail to pass the on-road test (see above). Alternatively he

can enforce dynamometer measurements directly without the need for on-road measurements and meanwhile

evaluate the on-road measurement systems (in pilot projects) until these are ready to serve as enforcement

tools.



6 RECOMMENDATIONS

From their investigations on IUC the authors believe that the following recommendations are worth-

while considering by the EC.

The engine classification within the USA NTE approach is based on the ESC cycle C speed with 2400

rpm as spill. Whether this is applicable for the EU needs to be confirmed.

Under the NTE approach the NTE 30 second window must be evaluated. Too small a window might

be undesirable because a high but short emission event can cause the engine to fail the test. Too large a win-

dow on the other hand might damp transients too much.

Test conditions, potentially influencing the test result, should be evaluated in practice. The amount of

influence has to be determined and the way how to cope with it should be given.

Real-life in-use HD vehicle data gathered in studies such as on the WHHD cycle should be examined

to help propose a more realistic emissions carve-out at a lower then 30% maximum power curve underneath

the engine’s torque-rpm diagram.

It might be advisable to extend certification testing to include NTE testing along the WHHD cycle.

This yields a firm link between a real-life certification cycle and in-use conformity testing as NTE testing is

a factor common to both.

The applicability of the USA IUC approach should be the subject of discussions with the engine

manufacturers and the EU member states, for example within the Motor Vehicle Emission Group (MVEG)

that is chaired by the EC. Thus a common European approach can be developed. Moreover, in the light of

harmonisation of emission regulations the EC and the USA EPA should confer on their intended approaches

towards IUC.

There are many possibilities to on-road testing depending on what approach to IUC will be taken. This

novel field should be further researched and discussed by the parties involved, especially with the engine and

vehicle manufacturers.

In the light of world wide harmonisation a common set of specifications for on-road systems should be

used across the USA and the EU. Also, the test protocol should be universal.

Special attention should be paid to chip tuning possibly present on vehicles selected for IUC testing.

The liability question needs investigation.

Given an IUC regulation in place, future concepts for emission control should be checked for their

IUC compatibility.



7 REFERENCES

[1] EPA - CFR Final Rule Part II 40 CFR Parts 85 and 86

Emissions control, Air pollution from 2004 and later model year heavy-duty highway engines and

vehicles; light-duty on-board diagnostics requirements revision

[2] R. Kolke, Umweltbundesamt

Experience, Results and Recommendations for In-Use Compliance Testing in Germany

Conference Intertech 15-17 October 2000, Berlin

[3] L. Olsson

Experience with and outlook for IUC Testing in Sweden


[4] W. Niederle, Umweltbundesamt

Heavy Duty IUC Testing in Germany-First experience and outlook


[5] I. Riemersma, TNO Automotive

Options for practical In-Use Compliance testing of HD vehicles


[6] http://www.arb.ca.gov/msprog/inusecom/inusecom.htm

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Control of air pollution from new motor vehicles: heavy-duty engine and vehicle standards and

highway diesel fuel sulphur control requirements

[8] EPA OTAQ EPA420-R-00-011

Control of emissions of air pollution from 2004 and later model year heavy-duty highway engines

and vehicles: Response to comments

[9] R. Gezelle

EPA’s in-use test program for heavy-duty trucks

SAE Government/Industry meeting May 16, 2001 Washington DC

[10] http://es.epa.gov/oeca/ore/aed/diesel/

[11] M. Gautam

Evaluation of mobile monitoring technologies for heavy-duty diesel-powered vehicle emissions

West Virginia University, March 9, 2000



[12] M. Gautam

Development of in-use testing procedures for heavy-duty diesel-powered vehicle emissions

West Virginia University, March 20, 2000

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9th CRC On-road vehicles emissions workshop, 19-21 April 1999, San Diego, California

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senfahrten

Automobil-Industrie Nr; 1/88

[16] D. Schürmann, Volkswagen

Messungen von Automobilabgasen bei Strassenfahrten

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Development of an on-board analyser for use on advanced low emission vehicles

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[18] T. Truex & J. Collins

Measurement of ambient roadway and vehicle exhaust emissions – An assessment of instrument

capability and initial on-road test results with an advanced low emission vehicle

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Real-time on-board measurement of mass emission of NOx, fuel consumption, road load, and en-

gine output for diesel vehicles

SAE Paper 2000-01-1141

[20] H. Frey

Measurement of on-road tailpipe CO, NO and hydrocarbon emissions using a portable instrument

Proceedings, Annual meeting of the air & waste management association, 24-28 June 2001, Or-

lando, Florida

[21] T. Durbin

Evaluation of the effects of biodiesel fuel on emissions from heavy-duty non-road vehicles

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2001

[22] http://www.sensors-inc.com



[23] G. Lenaers

A dedicated system for on-the-road exhaust emission measurements on vehicles

Poster Proceedings of the Third International Symposium on Transport and Air Pollution, 6-10

June 1994, Avignon, France

[24] Patrick Debal, Guido Lenaers and Erik Verhaeven

VOEMLow: Emission and Energy Measurement System as Development Tool for Clean Engines,

After-Treatment Systems and Power Trains,

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USA, submitted

[25] M.T. Sherman, K. Lennon and R.E. Chase, Ford Motor co.,

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[26] M. Landry, M. Guenther, K. Isbrecht and G. Stevens, Ford Motor co.

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Systems

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[27] EPA OTAQ EPA420-R-00-010

Regulatory Impact Analysis: Control of emissions of air pollution from highway heavy-duty en-

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[28] M. Gautam

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In-Use Compliance testing of passenger cars in the Netherlands


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year heavy-duty highway engines and vehicles; Revision of light duty truck definition



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ACEA, 1998

Websites

http://www.epa.gov/otaq/hd-hwy.htm

http://www.epa.gov/docs/fedrgstr/

http://www.dieselnet.com



8 ACRONYMS AND ABBREVIATIONS

A

ABT Averaging, Banking and Trading

ACEA Association des Constructeurs Européens d’Automobiles

ACERT Advanced Combustion Emission Reduction Technology

AECC Association for Emission Control by Catalyst

AECD Auxiliary Emission Control Device

ALAPCO Association of Local Air Pollution Control Officials

API American Petroleum Institute

APS Alternative Propulsion Systems

AOP Auto Oil Project

AUTh Aristotle University of Thessaloniki

B

BAR Bureau of Automotive Repairs

C

CAA Clean Air Act

CAP2000 Compliance Assurance Program 2000

CARB California Air Resources Board

CCMC Committee of Constructors of the Common Market

CDPF Catalysed Diesel Particulate Filter

CFR Code of Federal Regulations

CI Compression Ignition

CLA Chemi Luminescence Analyser

CLD Chemi Luminescence Detection

CLEPA Association of automotive component manufacturers

CNG Compressed Natural Gas

CRADA Cooperative Research And Development Agreement

CRC Coordinating Research Council

CRT Continuously Regenerating Trap

CTS Center for Transportation Studies

CVS Constant Volume Sampler



D

DDC Detroit Diesel Corporation

DF Deterioration Factor

DG ENTR Directory General ENTeRprise

DME DiMethyl Ether

DOC Diesel Oxidation Catalyst

DPF Diesel Particulate Filter

DPNR Diesel Particulate NOx Reduction

DRI Desert Research Institute

E

EC European Community

ECM Electronic Control Module

ECU Engine Control Unit

EDC European Driving Cycle

EEV Enhanced Environmental Friendly Vehicles

EGR Exhaust Gas Recirculation

ELR European Load Response test

EMA Engine Manufacturers Association

ENGVA European Natural Gas Vehicle Association

EOBD European On-Board Diagnostics

EPA Environment Protection Agency

ESC European Steady Cycle

EST Environmental Sustainable Transport

ETC European Transient Cycle

ETSC European Transport Safety Council

EUDC Extra Urban Driving Cycle

F

FBC Fuel Born Catalysts

FEL Family Emission Limits

FID Flame Ionisation Detector

FTIR Fourier Transform Infra Red spectroscopy

FTP Federal Test Procedure

G

g/bhp-hr gram per brake horse power hour



GC Gas Chromatograph

GCWR Gross Combined Weight Rating

GRPE GRoup on Pollution and Energy

GVWR Gross Vehicle Weight Rating

H

HC HydroCarbon

HCCI Homogeneous Charge Compression Ignition

HD Heavy Duty

HDCC Heavy Duty Chassis Cycle

HEUI Hydraulically activated Electronically controlled Unit Injector

HFID Heated Flame Ionisation Detector

I

ICE Internal Combustion Engine

IFC Interference Filter Correlation

I/M Inspection/Maintenance

IUC In-Use Compliance/Conformity

J

JAMA Japanese Automobile Manufacturers Association

L

LAT Laboratory of Applied Thermodynamics (University Thessaloniki)

LC Liquid Chromatography

LCA Life Cycle Analysis

LD Light Duty

LDV Light Duty Vehicle

LNG Liquefied Natural Gas

LPG Liquefied Petroleum Gas

M

MAEL Maximum Allowable Emissions Limit

MAP Manifold Air Pressure

MDT Micro Dilution Tunnel

MEMS Mobile Emissions Measurement System

MHDDE Medium Heavy-Duty Diesel Engines

MIRA Motor Industry Research Association

MSAT Mobile Source Air Toxic



MS Mass Spectroscopy

MVEG Motor Vehicle Emissions Group

MY Model/Make Year

N

NAAQS National Ambient Air Quality Standards

NCP Non Conformity Penalty

NDIR Non Dispersive Infra Red

NEDC New European Driving Cycle

NIOSH National Institute for Occupational Safety and Health

NMHC Non Methane Hydro Carbons

NMVOC Non Methane Volatile Organic Compounds

NVOF Non Volatile Organic Fraction

NPV Net Present Value

NTE Not To Exceed

NTP Non Thermal Plasma

NYBC New York Bus Cycle

O

OBD On-Board Diagnostics

OBM On-Board Monitoring/Measurement

OREMS On-Road Emission Measurement System

OTAQ Office of Transportation and Air Quality

P

PAH PolyAromatic Hydrocarbons

PBA Peter Brett Associates

PM Particulate Matter

PM10 Particulate Matter of 10 µm or less in diameter

PM2.5 Particulate Matter of 2,5 µm or less in diameter

Q

QC/QA Quality Control / Quality Assurance

R

RIA Regulatory Impact Analysis

RH Relative Humidity

RME Rape Methyl Ester

ROG Reactive Organic Gases



ROVER Real-time On-road Vehicle Emission Reporter

RPA Relative Positive Acceleration

RPM Revolutions Per Minute

RTD Resistive Temperature Detector

S

SAE Society of Automotive Engineers

SCR Selective Catalytic Reduction

SCRT Combination SCR & CRT

SIP State Implementation Plan

SI Spark Ignition

SOC State Of Charge

SOF Solid Soluble Organic Fraction

SUV Sport Utility Vehicle

T

TAA Type Approval Authority

TEOM Tapered Element Oscillating Balance

THC Total HydroCarbon

TNO Nederlandse Organisatie voor Toegepast Natuurwetenschappelijk Onder-

zoek

TPS Throttle PoSition

TWR Three Way Catalyst

U

UBA UmweltBundesAmt

UDC Urban Driving Cycle

UDDS Urban Dynamometer Driving Schedule

UEGO Universal Exhaust Gas Oxygen

UHEGO Universal Heated Exhaust Gas Oxygen

UHC Unburned HydroCarbons

UN United Nations

V

Vito Flemish Institute for Technological Research

VOC Volatile Organic Compound

VOEM Vito’s On the road Emission and energy Measurement system

VTG Variable Turbocharger Geometry



W

WHDC World Harmonised Heavy Duty engine test Cycle

WHHD World Harmonised Heavy Duty

WHSC World Harmonised Steady state Cycle



9 ANNEXES

Annex 1 Tables Questionnaire IUC

Annex 2 Delivery goals of CRADA



9.1 ANNEX 1: RESULTS QUESTIONNAIRE ON IN-USE COMPLIANCE



vehiclevehicle

vehiclevehicle

vehiclecom

ponentcom

ponentvehicle

component

vehiclea

bc

de

fg

hi

jYes

No M

aybeLow

er real emissions? Y, N

, or ??

N?

YY

?Y

?Y

n4

24

OBD

replace? Y, N, or ?

YY

YY

NY

NY

Yy

82

0O

BM replace? Y, N

or ?Y

YY

Y?

Y?

YN

?6

13

Responsible for testing (M

, O, TA, G

ov, other)TA, G

ovTA

TA, Gov

TA, Gov

TATA, gov

M, TA

TA, govM

Who to pay (M

. O. TA. G

ov, other)G

ovTA, G

ovG

ovG

ovM

, TA *gov

-G

ovM

/TAW

ho selects vehicles (M, O

. Ta, Gov, O

ther)G

ovTA

Gov

Gov

TAG

ovM

, TAM

, Gov

Who to do testing (M

, O. TA. G

ov. other)M

, TAM

, TAM

, TAM

, TAM

, Gov **

M, TA

M, TA

M, TA

Road test?

NY

NN

YN

YN

-3

5C

hassis dyno test?N

NN

NM

NM

NY

16

2Bench dyno test?

NN

YY

NN

NY

-3

5Bench dyno test: cycle?

ELR, ESC

ETC, ELR

, ESCELR

, ESCELR

, ECS

ESC, O

therELR

, ESC-

ELR, ESC

ETC, ESC

, other (NO

T ELR)

NTE lim

it? Y, N, M

(maybe)

MY

MN

YM

YM

-3

14

Com

ponent suppliers to have results? N

NN

NN

NY

NY

27

Database/results m

ade available?M

NM

MY

MY

Y-

n3

24

Age at first testing? Months

2424

2424

minim

um 24

24>12

36-

Age at first testing? 1000 km200

200200

200-

200>100

--

Frequency of IUC

testingO

nceO

nceO

nceO

nceO

nceO

nce-

once-

Random

selection of vehicles?Y

YY

YY

YY

Y-

8

Maintenance according to m

anufacturers specs?-

--

-Y

-Y

-2

Mandatory M

aintenance?Y

YY

-Y

-4

Tampering checked?

--

--

Y-

1C

heck maintenance log?

-Y

--

YY

-3

Functional check?Y

-1

OBD

Mem

ory Check?

Y-

1Precondition against m

anufacturers spec?-

What param

eters? (TBD = to be defined)

TBD

Dependant on final test

proceedureTBD

TBD

ESC, N

TE including transients

TBDIf engine dyno - ESC

?-

Y-

-Y

-Y

3

Road testing?

-

Unknow

n. W

orldwide

harmonised

proceedure desireable

--

Within N

TE range and

normal am

bient conditions

-steady state conditions

-N

Ox to be m

easured?-

--

-Y

-Y

-2

PM (sm

oke) to be measured?

--

--

Y-

Y-

2

Co and C

O2 to be m

easured?Y

-1

HC

to be measured?

Y-

1

Engine speed and load to be measured?

Y-

1

Exhaust gas temp to be m

easured?Y

-1

TA/CO

P results converted to IUC

results-

Unknow

n, extensive work

required. N

ot possible-

IUC

method

must be

included in type approval

requirement

(US

Proceedure), no need for

conversion algorithm

, reasonable averaging periods

necessary-

rated by truck manufacturer

only by using original ESC and ETC

test on a chassis dyno

* certification fee** M

anufacturer in first step



9.2 ANNEX 2: DELIVERY GOALS OF CRADA

The most immediate delivery goal is a commercially viable on-vehicle emissions measurement core

product with two specific optional modules. It must meet the core product and core product module goals

specified within this Statement of Work. It must in production and available for commercial sale and use

within 180 days after final CRADA approval. The following table summarizes the core product and priority

module goals in this Statement of Work.

Core Product Measurement and Data Acquisition Capabilities NOx mass rate (g/hr), ±10% @ 95% confidence, T-90=1 second

CO2 mass rate (g/hr), ±10% @ 95% confidence, T-90=1 second

Exhaust flow, must facilitate mass rate emissions quantification to stated

Temperature measurements (e.g. exhaust, ambient)

Pressure measurements (e.g. exhaust, ambient)

Ambient humidity, ±2%RH @ 95% confidence, T-90=1 minute

Engine speed, ±1 rpm, T-90=0.2 seconds

Engine torque measurement or estimate based on CAN/ECM and other parameters

CAN / ECM interface, records minimum of 12 channels at 1 Hz

GPS interface, records at minimum of 1 Hz

Data acquisition system: user friendly GUI, remote communications, calculations and display configurable on-the-

fly, easily accepts 3rd party modules, expandable data storage

Ability to simultaneously measure from two different locations in exhaust (i.e. up and downstream of an exhaust

after treatment device.)

Gasoline / SI Module (to be available with Core Product) CO mass rate (g/hr), ±10% @ 95% confidence, T-90=1 second

HC mass rate (g/hr), ±15% @ 95% confidence, T-90=1 second

λ, ±10% @ 95% confidence, T-90=30 milliseconds, < 30 second light-off

*NOx mass rate (g/hr), ±10% @ 95% confidence, T-90=1 second

*Required only if Core Product NOx instrument does not accurately quantify NOx from gasoline / SI engines.

Unattended Operation Module (to be available with Core Product) Enclosure: weatherproof, tamperproof, theft-resistant, pass-through connections

Extended power management: provides 1-week sleep mode power, recharges via vehicle power without affecting

engine operation

EPA considers system integration as imperative to ease of use. Managing multiple hardware components in

limited space on moving vehicles is undesirable.

for heavy-duty vehicles final...

Documents