development of federal aviation new roughness standard … albert larkin erpug... · roughness...

Presented to: European Road Profiler User

Group Forum

By: Al Larkin, FAA Airport Pavement R & D

Date: October 19, 2017

Federal AviationAdministrationDevelopment of

New Roughness

Standard for In-

Service Airport

Pavement

Federal AviationAdministration

European Road Profiler User Group Forum

October 19, 20172

Presentation Outline

• Background

• Airport Pavement Roughness Simulator

Project

• New Pavement Roughness Index Statistical

Analysis

• Overview of New Pavement Roughness

Index Model Development

• Conclusion



October 19, 20173

Data Collection

• Background• Current airport pavement surface roughness requires high standards

to control construction quality. Upper limit of straightedge indices

for each pavement type is defined by FAA AC 150/5370-10G,

Standards for Specifying Construction of Airports.

• Identified the need to develop a reliable method to quantify

roughness on in-service airport pavement surfaces.

• The FAA’s B737-800 and A330-200 full flight simulators study at Mike

Monroney Aeronautical Center in Oklahoma City since 2008.

• Test scenarios were developed based on the National Cooperative

Highway Research Program (NCHRP) highway rideability studies.

• Evaluated correlations between the FAA simulator project results at

the FAA’s B737-800 and A330-200 simulators and roughness indices

calculated by ProFAA the FAA’s pavement profile software.



October 19, 20174

B737-800 Flight Simulator

● FAA Mike Monroney

Aeronautical Center in

Oklahoma City

● Level D Certified Full

Flight Simulator

● Six-degree-of-freedom

motion system

● High resolution visual

display and sound system



October 19, 20175

Pilot Rating Procedure

Pilot Rating from B737 Simulator

●Taxiway and runway profiles selected from

U.S. and foreign airports to provide a wide

range of surface roughness

• Each scenario provides a 30 second profile

section

• 40 constant speed taxiway scenarios – 37

km/hr. (20 knots)

• 40 constant speed runway scenarios – 185

km/hr. (100 knots)

• Scenarios provide automated movement

along the profile sections with no pilot input

required



October 19, 20176

Airport Pavement Roughness ThresholdsISO Roughness

Index

(B737-800)

Index Value

When 5% of

Pilots Rate the

Taxiway as

Unacceptable

Index Value

When 10% of

Pilots Rate the

Taxiway as

Unacceptable

Index Value

When 50% of

Pilots Rate the

Taxiway as

Unacceptable

Index Value

When 5% of

Pilots Rate the

Runway as

Unacceptable

Index Value

When 10% of

Pilots Rate the

Runway as

Unacceptable

Index Value

When 50% of

Pilots Rate the

Runway as

Unacceptable

Weighted RMS

(m/s2)0.31 0.39 0.67 0.35 0.47 0.91

Weighted

MTVV (m/s2)0.71 0.94 1.72 0.68 0.99 1.91

Weighted VDV

(m/s1.75)4.11 5.32 9.29 4.16 5.66 10.88

DKup (m/s2) 1.82 2.40 4.45 1.69 2.40 4.81

Weighted RMS m/s2 Discomfort Level

0-0.315 not uncomfortable

0.315-0.63 a little uncomfortable

0.5-1.0 fairly uncomfortable

0.8-1.6 uncomfortable

1.25-2.5 very uncomfortable

> 2.0 extremely uncomfortable



October 19, 20177

Statistical Analysis for New

Roughness Index Development

• Evaluate the correlations between ProFAA indices

and ISO indices.

• Divide data into groups: runway/taxiway and

B737/A330.

• Develop regression models between ProFAA

indices and ISO indices for each data group using

linear regression analysis techniques.

• Choose the best regression model for the new

roughness index development

• New roughness index may be developed using ISO

indices based on the regression models



October 19, 20178

Statistical Analysis

• Comparison Between B737 and A330 Simulation Results

• It is not recommended to mix the simulation results from

B737 and A330 together since different types of aircraft have

different acceleration response to the runway profiles.

• Therefore, a comparative study was performed.

• It was found that the simulation results from each simulator

are strongly correlated with R2 > 0.98. The B737 has a higher

acceleration rate and lower pilot subject rating than A330,

which is reasonable since bigger aircraft has smaller

acceleration response and better pilot rating.



October 19, 20179

Wavelength Analysis

• Artificial Haversine Single Bump

• Acceleration at Center of Gravity

• Acceleration at Cockpit• Acceleration at Cockpit



October 19, 201710

Proposed Steps for the Statistical Analysis of

the New Index Development

1. Consider both user’s rideability and pavement surface conditions for in-service airport pavements.

2. Correlate Cockpit Accelerations (g) from aircraft simulator with current pavement roughness indices in ProFAA using statistical analysis.

3. Select the ProFAA index with the best correlation model as a baseline for new index development.

4. Compare wavelength sensitivity reflecting constructability (+drainage) with aircraft simulation studies.

5. Select appropriate independent parameters for runway/taxiway.

6. Refine the correlation model for new index development



October 19, 201711

B737 Runway – Boeing Bump Index

BBIAverage = fR * ACCWtRMS

fR = Roughness Factor Constant (0.2559 in current study)



October 19, 201712

Statistical Analysis Summary and Conclusions

• Statistical regression analysis was conducted to correlate

ProFAA computed indices with Boeing 737-800 and Airbus A330-

200 aircraft simulators test results.

• It can be found that the indices are directly related to WtRMS of

acceleration. WtRMS shows good correlation with ProFAA

computed indices.

• Due to travel speed, consider runways and taxiways separately.

• Boeing Bump Index (BBI) has a very good linear relationship with

WtRMS for runways. This correlation model can be used for the

new roughness index development.

• For taxiways, IRI and Profile Index have good correlations with

simulator data.



October 19, 201713

Aircraft Simulation Model – to be Improved

• Known Parameters

– Aircraft type

• Weight

• Wheel Base Dimensions

• Gear Configuration

– Aircraft Speed

– Wavelength of pavement profile

• Unknown Parameters

– Aircraft Gear Dynamics



October 19, 201714

Proposed Steps for New Index Model

Development

1. Simulate the vertical acceleration at the aircraft cockpit using the aircraft simulation model by considering all the parameters.

2. Validate the simulation model using field test of the FAA owned B727 airplane at the Atlantic City (ACY) airport.

3. Implement the simulation model into ProFAA to improve the aircraft simulation function.

4. In ProFAA, for each input runway profile, the vertical acceleration at the cockpit will be calculated using aircraft simulation for each sample spacing (user can define).

5. The vertical acceleration will then be converted to new roughness index by the roughness factor constant fR.



October 19, 201715

Proposed Steps for New Index Model

Development

6. The new index at each sample spacing will be calculated. The average value for the whole runway section will also be computed.

7. Evaluate the new roughness index threshold criteria.

– Single Event

– Multiple Events



October 19, 201716

Aircraft Simulation Model

Pavement Profile Vertical Acceleration at the

Cockpit is more critical



October 19, 201717

Model Validation – B727 in ACY

FAA Owned Boeing 727



October 19, 201718

Model Validation – B727 in ACY



October 19, 201719

Model Implementation in ProFAA



October 19, 201720

New Index Threshold

• Single index at certain location (single event) : < 1 (current

Advisory Circular)

• Average index at the whole section (multiple events) : criteria

based on pilot’s rating from WtRMS of acceleration by applying

the roughness factor constant.

Weighted RMS m/s2 Discomfort Level0-0.315 not uncomfortable

0.315-0.63 a little uncomfortable

0.5-1.0 fairly uncomfortable

0.8-1.6 uncomfortable

1.25-2.5 very uncomfortable

> 2.0 extremely uncomfortable



October 19, 201721

Conclusion• It is recommended to separate runway and taxiway data.

• Regression Results on Runways

– For the runway, ProFAA computed indices have good correlation with the WtRMS of

acceleration from aircraft simulation for both B737 and A330 simulators.

– B737 models have good agreement with A330 models respectively on the runways.

A conversion factor on WtRMS can be applied between B737 models and A330

models.

– Boeing Bump Index has the best correlation with the WtRMS on the runways

compared to the other ProFAA computed indices (R2 > 0.98). Therefore, it is

recommended to use Boeing Bump Index model for new roughness index

development for runways.

• Regression Results on Taxiways

– For the taxiway, IRI, SE, PI, and BP have good correlations with the aircraft

simulation results, which can be used for new roughness index development.

However, the correlation between BB and aircraft simulation results was not good.

• Based on the regression analysis, WtRMS was selected as the independent predictor to

correlate with ProFAA computed indices. It is recommended to use the runway data only

for the new roughness index development based on acceleration response at this stage.



October 19, 201722

Contact

• Albert Larkin

• Airport Technology R & D

• William J. Hughes Technical Center

• ANG - E262

• (609) 485 – 5552

• [email protected]

development of federal aviation new roughness standard … albert larkin erpug... · roughness...

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