aacra street lighting manual

8/10/2019 AACRA Street Lighting Manual

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GUIDELINE 7AACRA STREET LIGHTING DESIGN MANUAL

FINAL - November 2004 Section 1 IntroductionPage 1-1

1 INTRODUCTION

1.1 Addis Ababa City Roads Authority

The Addis Ababa City Roads Authority (AACRA) was established by the Addis Ababa City

Government in 1998.

The role of AACRA is to plan, construct and maintain the city road network including the street

lighting.

1.2 Contractors to AACRA

In some cases private developers contract to construct roads in new areas of the City. These

roads are handed over to AACRA to maintain. In accordance with AACRA Legislative Framework

AACRA has the power to require that the private developer must construct the roads and all related

facilities, including street lighting, in accordance with AACRA requirements and under AACRA

supervision.

1.3 Legislative Framework

The Addis Ababa City Roads Authority Establishment Regulations No7/1998 defines the powers

and duties of the AACRA. These regulations include powers with respect to road/street lighting.

The powers with respect to street lighting include, but are not limited to:

a) Initiate policies and laws with regard to road network, construction, protection and useof roads.

b) Determine design standards for roads and implement same.

c) Construct roads on its own or have them constructed through contractors.

d) Determine standards give permit and supervise roads to be constructed by the

society, by groups or by private individuals, by governmental or non governmental

organizations; and, where necessary, it shall, in accordance with its own directives,

provide appropriate technical & material support.

e) Cause the installation and protection of road/street lights.

1.4 Objectives

The objectives of the preparation of a Street Lighting Design Manual include:

a) To provide AACRA with design standards. which are in line with current best

international practice

b) To provide a maintenance framework which will ensure that best performance of the

existing and future Street Lighting installations is sustained for the lifetime of the

equipment.

c) To provide guidelines for cost effective upgrading of the existing street lightinginstallations.


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Section 1 Introduction FINAL - November 2004Page 1-2

One key consideration is lighting design to reduce the risk of traffic accidents at night. For

comparable traffic volumes, road accidents at night are disproportionately high in numbers and

severity compared to daytime. Depending on the road and traffic classification, studies show the

accident savings to more than offset the cost of lighting (refer 8.5 Publications of the InternationalCommission on Illumination (CIE)

Technical report CIE 93 1992).


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FINAL - November 2004 Section 2 Interested PartiesPage 2-1

2 INTERESTED PARTIES

There are a number of stakeholders who have an interest in street lighting

2.1 Ethiopian Electric Power Corporation (EEPCO)

EEPCO supplies all electric power in Ethiopia. Street lighting installations must comply with the

safety and metering regulations of EEPCO before power can be connected.

EEPCO advised in September 2002 that the tariff for street lighting was currently 0.3970 birr per

kilowatt hour.

2.2 EEPCO Historic Role in Street Lighting

Before the formation of AACRA, EEPCO had sole responsibility for deciding which streets were to

be lit and for design, construction and maintenance of street lighting.

After the formation of AACRA provision of street lighting became the responsibility of AACRA who

contracted this work out to EEPCO.

Many existing street lights that have become the responsibility of AACRA are mounted on poles,

which also carry open wire power distribution systems and therefore remain the property of

EEPCO.

AACRA is now charged under its Establishment Regulations with determining and implementing

design standards for roads, including Street lighting.

2.3 Other Services in the Road Reserve

The location of all other services in the road reserve affects the space that is available for the

installation of street lighting and vice versa. Installation of street lighting requires space for poles,

cabling and facilities. It also requires coordination with the space needed for other services.

All of the following organizations are interested parties in street lighting because they have facilities

located in the road reserve. These facilities may conflict with the space requirements for

installation of street of street lighting. Coordination of all these facilities is essential.

2.3.1 Stormwater by AACRA.

Provision for storm water drainage requires either open channels or underground piping in the roadreserve.

2.3.2 Telephone by Ethiopia Telecommunications Corporation (ETC).

Telecommunications services are distributed by both overhead and underground lines, usually in

the road reserve. There are minimum clearance requirements to be observed between

telecommunications and other electrical services to avoid electrical interference refer Clause

4.10.2.


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Section 2 Interested Parties FINAL - November 2004Page 2-2

2.3.3 Electrical distribut ion by EEPCO.

EEPCO has an extensive 15 kV and 380 volt distribution system mostly on overhead poles in the

road reserve.

Clearance requirements between street lighting and electrical distribution systems are discussed inClause 4.10 Coordination with other services

2.3.4 Water and Sewerage by Addis Ababa Water and Sewerage Author ity

(AAWSA).

Water distribution and sewerage collection pipe work is installed in road reserves by AAWSA.

2.3.5 Traffic Signs by AACRA

Traffic signs must not be obscured by the placement of street light poles however there is usually

some flexibility in the placement of signs. Traffic signs may be mounted on street light poles if the

street lighting poles are in a suitable location. It is recommended that traffic signs including street

names are faced with retro-reflective material complying with ASTM D4956-01 Standard

Specification for Retro-reflective Sheeting for Traffic Control, so that they will be adequately

illuminated by vehicle headlights without the need for supplementary illumination. Where it is not

possible to mount traffic signs in a position where they will be illuminated by vehicle headlights, it is

recommended that supplementary illumination providing a minimum vertical illuminance of 20 lux

should be used. Supplementary illumination may be provided by conventional lights or by solar

powered light emitting diodes. An example of commercially available solar powered illuminated

signs is shown at reference 8.7.11.

2.3.6 Traffic Light Signals by AACRA

Traffic light signals can share a common mounting pole with street lights.

Traffic light signals must not be obscured by the placement of street light poles or by the placement

of traffic signs. Traffic light signals may be fed by the street lighting power supply network provided

that the lighting power supply is switched ON 24 hours per day.

2.3.7 Sample Designs for Coordination of Service Locations

Sample designs for coordination of space allocation between services are included in concept

sketches in The Addis Ababa City Road Network (final draft) April 2002 produced by the Office for

the Revision of the Addis Ababa Master Plan (ORAAMP)

Further examples are given in reference 8.6.2

The arrangements change in different areas to suit the space available in the footpath for the

installation of street lighting cables and other underground services. Underground services, except

roadway crossings, are not usually installed directly under the vehicle traffic lanes because of the

disruption to traffic that would occur during maintenance and alteration work.


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2.4 Ethiopian Civil Aviation Authori ty

Ethiopian Civil Aviation Authority (ECAA) operates the international airport within the City of Addis

Ababa. ECAA is an active member of the International Civil Aviation Organization and will have

requirements to ensure that street lighting does not interfere with aircraft navigational lighting at

any airport.

There is also an airport known as The Old Airport now operated by the military. Whilst the military

may or may not have special lighting requirements in the vicinity of this airport it would be prudent

to design any street lighting in the vicinity of this airport to comply with the regulations for a civil

airport.

The requirements for street lighting in the vicinity of airports are usually applied uniformly

worldwide.

2.4.1 Typical Requirements for Street Lighting near Airports

Detailed requirements should always be checked with ECAA before starting any street lighting

work within 6000 metre of the airport boundary. Typical requirements (based on international

requirements) include:

a) An existing or proposed street light in the vicinity of an airport which, by reason of its

intensity configuration or colour might endanger the safety of aircraft is to be notified to

ECAA for a safety assessment.

b) In general the primary area in the vicinity of an airport can be taken as within a

rectangular area the length of which extends at least 4500 m before each threshold andthe width of which is at least 750m either side of the extended runway centreline as

shown in the Figure 1.

c) ECAA may vary this requirement for the smaller airports. ECAA requirements should

always be checked when planning any street lighting within 6 km of airports.

2.4.2 Luminaries near Airports

In general luminaires should be selected because their graded light emission above the

horizontal conforms to the zone requirement shown in Figure 2-1. Alternatively aeroscreen

luminaires designed and installed to limit the light emission above the horizontal to zero

should be used.

2.4.3 Coloured Lights near Airports

Coloured lights are likely to cause conflict irrespective of their intensity as coloured lights

are used to identify different airport facilities. Proposals for coloured lights near airports

should be referred to ECAA for guidance.


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Figure 2-1: Lighting within 6km of Airpor t

Source http://www.casa.gov.au/avreg/rules/download/rpa/chap12.pdf

2.5 City Government of Addis Ababa

The City Government will require street lighting to conform to the City Master Plan.

2.6 Quality and Standards Authori ty of Ethiopia (QASA)

The ETHIOPIAN STANDARDS 2002 CATALOGUE does not list any Ethiopian standards for street

lighting. QASA may become involved in this area of standardization in the future.

Source http://www.qsae.org/index.html


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2.7 International Best Practice

2.7.1 General

AACRA requires the street lighting to conform to best international practice whilst recognizing that itwill not be possible to update all of the existing lighting in the city immediately.

Best practice requires that the designed amount of light is provided to assist the safe and

comfortable movement of vehicles and pedestrians and to provide a sense of security from crime.

There are five factors which are critical to the achievement of best practice in street lighting. These

are:

a) Provision of a reliable electric power supply

b) Choice of suitable lamps (light sources) to produce the light effectively

c) Choice of suitable luminaires to house the lamps and distribute the light

d) Positioning of the luminaires to distribute the light effectively

e) Maintenance of the street lighting system to ensure that it continues to deliver the required

performance.

There are other desirable factors, which should be targeted for best practice in street lighting.

These include:

a) Underground wiring systems for security and attractive appearance

b) Appropriate supporting poles for long life and attractive appearance

This Lighting Design Manual reflects technical requirements set out in Australian and New Zealandstandards. At the time of preparation of this Design Manual there were no Ethiopian standards for

street lighting (refer Clause 2.6. Quality and Standards Authority of Ethiopia (QASA))

Australian and New Zealand standards satisfy best international practice and are also used in

Hong Kong. Equally satisfactory best practice results in street lighting can be achieved by the use

of other recognised national standards for example British Standard 5489 Road Lighting

(Reference 8.7.6.) or the publications of CIE (Commission Internationale de

l'clairage/International Commission on Illumination) (Reference 8.5)

The designs will be adapted to suit conditions in Addis Ababa.

Standards in this series from which technical requirements are drawn include:

a) AS 1852 International Electrotechnical Vocabulary. This standard is identical with the

corresponding volume of International Electrotechnical Commission Standard IEC50.

This standard compares the terms used for electrotechnology including lighting in various

languages.

b) AS/NZS 1158 Road Lighting. This defines lighting requirements for various categories of

roads and includes a design program.

c) AS 1798 Preferred Dimensions of Poles and bracket arms defines a method of ensuring

compatibility of poles, bracket arms and the attachment points for luminaires.

d) AS 3771 Road Lighting Luminaires with Integral Control Gear sets out standardrequirements for luminaires.


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e) AS/NZS 3827 Lighting System Performance Accuracies and Tolerances sets out

performance requirements

f) AS/NZS 4065 Concrete Utility Services Poles lists requirements for concrete poles

It is probable that suppliers will offer to AACRA designs and materials which comply with their own

National Standards. When these alternatives are offered, it is recommended that the suppliers be

required to demonstrate, by comparing the standards that the designs and equipment offered are

equal to or better than the AACRA specified requirements. It is also recommended that AACRA

insists that illumination levels meet the specified AACRA requirements, however the delivery of

materials complying with recognised national standards may be satisfactory, subject to inspection

and approval by AACRA.

2.7.2 Prior ity Guidelines

The following priority guidelines for the upgrading of the street lighting to conform to best

international practice are proposed.

New Developments

Wherever a new residential or commercial property development is carried out within the area

controlled by AACRA, the roads should be constructed and the services including street lighting

should be installed in accordance with AACRA design requirements and paid for by the Developer.

Subject to AACRA constitution, a contribution towards the cost of ongoing operation and

maintenance may also be required before new street lighting is handed over to AACRA for

maintenance and operation.

Maintenance

Maintenance, cleaning and re-lamping of all those existing streetlights that are capable of

operating, will be a cost effective method of quickly improving street lighting performance, but will

not necessarily achieve best international practice immediately. Maintenance may include

replacement of lamp ballasts, and fitting of covers to control gear openings in poles, where covers

are missing. Maintenance may also include the replacement of unsatisfactory lighting controls,

such as the one illustrated, with weatherproof equipment.

Where maintenance of an existing streetlight is not economical, it should be replaced as

recommended in Clause 4.3 Lighting Equipment.


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Accident black spots

All areas where there is an above average occurrence of night time accidents should be

considered for priority upgrade to best international practice lighting.

Crime hot spots

All areas where there is an above average occurrence of night time criminal activity should be

considered for priority upgrade to best international practice lighting.

Traffic volumes

Upgrading the lighting of streets with high traffic volumes should take priority over upgrading the

lighting of streets with lower traffic volumes. However, when lighting on a high traffic volume street

is upgraded attention should be paid to the lighting at all intersections including those where the

intersecting street carries a low traffic volume.

As noted in Clause Error! Reference source not found.Pole Construction, international best

practice does not exclude the use of poles that support both street lighting and overhead powerdistribution cables. Because there are areas in Addis Ababa where overhead power distribution

cables are used it will be cost effective to consider using the existing power distribution poles to

support upgraded street lighting, provided that agreement can be reached with EEPCO. The

spacing of luminaires will be dictated by the spacings of existing electricity distribution poles. This

will limit the choices available to the lighting designer but may allow a satisfactory result to be

achieved at an appropriate cost.


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FINAL - November 2004 Section 3 Climate and EnvironmentPage 3-1

3 CLIMATE AND ENVIRONMENT

All electrical equipment, including street lighting, is subject to the effects of the environment in

which it is installed. It must be specified to be resistant to these effects. The accuracy of theinformation listed below should be checked with the National Meteorological Service Agency who

may have longer term climatic records available.

The major climatic and environmental factors that can affect street lighting are described in the

following sub-sections.

3.1 Fog

Fog reduces the effectiveness of street lighting. Fog also deposits surface moisture on insulating

materials and metals. This reduces insulation resistance and promotes corrosion of metals. Addis

Ababa is not severely affected by fog

3.2 Rainfall and Insects

Luminaires should be well sealed against the entry of rainfall and insects. Both these factors

influence the intervals between cleaning of luminaires. Monthly rainfall in Addis Ababa ranges from

approximately 8 mm in November to approximately 278 mm in August with an average annual

rainfall of 1178 mm. (Some sources quote rainfall of between 1200 and 1500 mm annually) Some

collections of insects have been observed in older street lights.

3.3 Atmospheric Pollution

Atmospheric pollution causes luminaires to become dirty inside and outside and influences the

intervals between cleaning. It also deposits on insulating materials and lowers insulation

resistance. Air pollution levels in Addis Ababa would generally be classified as high.

Addis Ababa is subject to visible exhaust smoke from vehicles. The powers and duties which allow

AACRA to initiate policies and laws with regard to the use of roads may be sufficient to allow

AACRA to regulate exhaust smoke from vehicles.

3.4 Wind

The maximum expected wind velocity sets the minimum force that street light poles must be

designed to withstand. The maximum expected wind velocity advised by Addis Ababa airport is 50

knots. This will not require any special design considerations as it is lower than the wind velocity

for which luminaires and poles are normally designed.

3.5 Temperature

Extremely low temperature can affect the ease with which lamps start. Addis Ababa has a

moderate monthly average temperature range of between 80C and 240C approximately. However

Addis Ababa is in an area which is classified by the atlas of Ethiopia as subject to frequent frosts.

Addis Ababa is also subject to a daily temperature range of up to 32.3 degrees Centigrade. This

will tend to promote condensation in electrical equipment.


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Section 3 Climate and Environment FINAL - November 2004Page 3-2

3.6 General Climate

Addis Ababa is in a region classified by the atlas of Ethiopia as Warm Temperate Climate.

Because of the high range of daily temperature and humidity it will be appropriate to specify that all

electrical equipment must be tropic proof. This will ensure that the equipment supplied will beresistant to corrosion.

3.7 Solar Radiation

Addis Ababa is at an elevation of approximately 2400 metres and the atlas of Ethiopia reports that

it experiences 200 300 hours of sunshine per month. The combination of high elevation and high

level of sunshine will ensure that high levels of ultraviolet radiation (UV) are experienced. Electrical

equipment must be specified to be UV resistant.

The following climatic and environmental factors should be included in specifications for street

lighting electrical equipment for use in Addis Ababa.

Table 3-1 Climate and Envi ronment Requirements

Tropic Proofing Required

Annual Rainfall 1200 mm

Atmospheric pollution level High

Wind Gusts to 50 knots

Monthly average 8 24 degrees Centigrade

Daily range up to 32 degrees Centigrade

Temperature

Minimum subject to frosts

Ultraviolet radiation level High

Elevation 2400 metres above sea level.


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FINAL - November 2004 Section 4 Requirements for LightingPage 4-1

4 REQUIREMENTS FOR LIGHTING

4.1 General Requirements

The objective of major road lighting is to provide a lighted environment that assists the safe and

comfortable movement of vehicular and pedestrian traffic at night. However, the visual

requirements of the motorist predominate. To accomplish this, the lighting shall reveal the

alignment of the road ahead, kerbs, footpaths, road furniture and surface imperfections, together

with other road users including pedestrians, cyclists and vehicles, and their movements, and any

other animate or inanimate obstacles.

The objective of minor road and pedestrian area lighting is to provide a lighted environment to

assist pedestrians to orient themselves, detect potential hazards and to discourage crime against

both people and property. The lighting, with certain exceptions, is not meant to provide drivers with

adequate visibility if motor vehicle traffic is present at the location; for this the vehicle headlights are

used. The exceptions are where there is interactive pedestrian and vehicular activity in designated

areas, e.g. transport interchanges, car parks.

Accident black spots, where multiple night-time accidents have occurred are listed in Clause 2.7.2

Priority Guidelines as a locality where lighting upgrades may be required. It is recommended that

the following items be considered: -

Whether the collisions are between vehicles, between vehicles and pedestrians between

vehicles and animals or between vehicles and stationary objects, including street light

poles.

Whether there are other factors, such as glare from vehicle headlights, glare frombuildings or advertising signs, obstruction of illumination by trees or other objects or driver

distractions such as the movement of animals, which may contribute to the cause of

collisions. In this case the solution should attempt to cure the specific cause(s) of the

accidents, because increased illumination levels may not cure the problem.

If the collisions are between vehicles or between vehicles and pedestrians or between

vehicles and animals the solution may involve increasing the illumination, installing traffic

lights or roundabouts or controlling pedestrian or animal access.

If the collisions are between vehicles and fixed objects the solutions may include moving

the fixed object(s) to a safer location, increasing illumination or providing retroreflectivemarkers to identify the fixed object. The provision of protective barriers around the fixed

objects may or may not provide a solution in any individual case. An inappropriate barrier

may introduce another collision hazard but an appropriate barrier may redirect traffic flow

away from the hazard.

4.2 Design Illumination Levels for Different Classes of Roads

The Road Lighting Standard AS 1158, a copy of which was handed over with this manual,

classifies Public Lighting into two broad categories:

(a) Category V Lighting - Lighting which is applicable to roads on which the visual

requirements of motorists are dominant, e.g. major roads.


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Section 4 Requirements for Lighting FINAL - November 2004Page 4-2

(b) Category P Lighting - Lighting which is applicable to roads and outdoor public areas where

the visual requirements of pedestrians are dominant e.g. minor roads, car parks, pathways,

etc.

These category names can conveniently be adopted for use in Addis Ababa and the principal

technical requirements for each recommended category are included in the manual.

The Standard also makes provision for supplementary lighting at pedestrian crossings.

4.2.1 Hierarchy of Roads

In Addis Ababa there are four classes of roads outlined in the Planning and Design Framework in

Chapter 1 of the Geometric Design Manual reference 8.1 AACRA Road Design Manuals.

These are: -

(a) Freeways and controlled access arterial roads (Principal Arterial Streets)

(b) Sub-arterial roads

(c) Collector roads

(d) Local roads

The Geometric Design Manual recognises that where existing arterial and sub-arterial roads are

being upgraded full control of access to adjacent properties may not be possible.

4.2.2 Illumination Levels for each Class of Road

The Addis Ababa City Road Network (final draft) April 2002 produced by the Office for the Revision

of the Addis Ababa Master Plan (ORAAMP) includes concept sketches for roads of various widths.

Appropriate illumination levels recommended for each category of road will be as follows: -

Principal Ar terial Streets

Those streets nominated in the City Road Network (final draft) plan as principal arterial streets

(PAS) range from a recommended width of 20 metres upwards


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Table 4-1:- Conceptual widths of Principal Arterial Streets (Apr il 2002 Master Plan)

Total Width

Metres

Footpath

Metres

Drain

Metres

Vehicle

Carriageway

Median

20 alternative 1 3.5 and 3.5 1.5 12

20 alternative 2 3.5 and 3.5 13

25 alternative 1 2.5 and 2.5 1 and 1 8.5 and 8.5 1

25 alternative 2 2.5 and 2.5 1 and 1 8 and 8 2

30 alternative 1 4.5 and 4.5 10 and 10 1

30 alternative 2 3.5 and 3.5 10.5 and 10.5 2

40 5 and 5 5.5 & 7 & 7 & 5.5 1.5 & 2 & 1.5

50 5 and 5 6 & 10.5 & 10.5 & 6 2.5 & 2 & 2.5

60 5 and 5 6 & 14.25 & 14.25 & 6 1.75 & 6 & 1.75

Existing Principal Arterial Streets nominated in the April 2002 Master Plan have either some

pedestrian access or full pedestrian access. This corresponds to Freeways and Arterial Roads

where access is not fully controlled for which lighting to Category V1 to AS/NZS 1158.1.1:1997

plus supplementary lighting at pedestrian crossings to AS1158.4:1987 is recommended. Category

V1 is comparable (but not identical) to BS5489:1992 Part 2 Category 2/1.

The appropriate technical parameters for each category of lighting will be found in section 4.2.3.

This category of illumination is appropriate for arterial or main roads with mixed vehicle and

pedestrian traffic, high to very high vehicle and pedestrian volumes, moderate to low vehicle

speeds, stationary vehicles alongside the carriageway, through and local traffic and high traffic

generation from properties abutting the road.

Future Principal Arterial Streets may have no pedestrian or property access. An example is the

Ring Road under construction in 2002 where pedestrians and adjacent properties have access

restricted to the service roads on each side of the main carriageway.

Principal Arterial Streets with no pedestrian or adjacent property access correspond to Freeways

and Arterial roads with vehicle traffic only (no pedestrian or property access) for which lighting to

Category V3 to AS/NZS 1158.1.1:1997 is recommended.This category of illumination is appropriate for divided highways for through traffic with high to very

high vehicle volume and high speeds, no access for traffic between interchanges and with grade

separation at all interchanges with the characteristics of vehicle traffic only,.

Category V3 illumination is also appropriate for arterial roads that predominantly carry through

traffic with moderate to low vehicle speeds. These roads may have mixed vehicle and pedestrian

traffic, moderate to high vehicle volume, high pedestrian volumes, stationary vehicles alongside the

carriageway, some local traffic and moderate traffic generation from properties abutting the road.


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Sub Arterial Streets

The streets nominated Addis Ababa City Road Network (final draft) April 2002 produced by

ORAAMP as sub-arterial streets (SAS) range from a recommended width of 20 metres to 40

metres.

Table 4-2:- Conceptual widths of Sub-arterial Streets (April 2002 Master Plan)

Total Width

Metres

Footpath

Metres

Drain

Metres

Vehicle

Carriageway

Median







40 5 and 5 5.5 & 7 & 7 & 5.5 1.5 & 2 & 1.5

Sub Arterial Streets in the City Road Network (final draft) correspond to Sub-arterial roads with

recommended lighting Category V4 to AS/NZS 1158.1.1:1997.

This category of illumination is appropriate for sub-arterial roads, which connect arterial roads to

areas of development or which carry traffic directly from one area to another area with mixedvehicle and pedestrian traffic, moderate vehicle volume, low pedestrian volume, moderate to low

vehicle speeds and low traffic generation from properties abutting the road.

Collector Roads

The Addis Ababa City Road Network (final draft) April 2002 produced by ORAAMP includes

concept sketches for roads of various widths. Collector road reserve widths are not specifically

nominated. Observation of the function of streets indicates that streets which have up to 30 metre

widths with only one traffic lane constructed at present, act as collectors. An example of a 30

metre wide road reserve that acts as a collector is the street which runs past Bole

telecommunications branch office towards St Saviours church.


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Table 4-3:- Conceptual w idths of Collector Roads (Apri l 2002 Master Plan)

Total Width

Metres

Footpath

Metres

Drain

Metres

Vehicle

Carriageway

Median


15 alternative 2 3.5 and 3.5 2 6







Collector streets in Addis Ababa the recommended lighting category is P3 to AS/NZS

1158.3.1:1997.

This category of illumination is appropriate for collector or non-arterial roads which collect and

distribute traffic in an area, as well as serving abutting properties. These are roads with mixed

vehicle and pedestrian traffic, medium pedestrian volumes and low risk of crime.

Local Streets

The Addis Ababa City Road Network (final draft) April 2002 produced by ORAAMP envisages localroads. The following widths of roads have been selected from the concept sketches as

appropriate to be considered as local roads for the purpose of street lighting applications.


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Table 4-4:- Conceptual widths of Local Streets (April 2002 Master Plan)

Total Width

Metres

Footpath

Metres

Drain

Metres

Vehicle

Carriageway

6 2 0.5 3.5

8 2 0.5 5.5

10 alternative 1 2 and 1.5 1 5.5

10 alternative 2 2.5 1.5 6

10 alternative 3 3 and 1.5 - 5.5

12 alternative1 2.5 and 1.5 1.5 6.5

12 alternative 2 2.5 1.5 8.5


15 alternative 2 3.5 and 3.5 2 6

Local roads in Addis Ababa correspond to Local roads Category P4 lighting level to AS/NZS

1158.3.1:1999.

This category of illumination is appropriate for local roads or streets used primarily for access to

abutting properties, including residential properties. These are roads with mixed vehicle and

pedestrian traffic, low pedestrian volumes and low risk of crime.

It is also appropriate for pedestrian or cycle oriented pathways with pedestrian or cycle traffic only

where pedestrian and cycle activity is low, and where there is a low risk of crime.

In areas where there is a need to enhance prestige or where there is a high risk of crime a higher

category of lighting up to category P 1 may be needed.

Car Parks

Car parks may be constructed in the future by AACRA or private developers of shopping centres

for whose road works (including lighting) AACRA will have to give planning permission.

Because car parks require crime prevention and secure pedestrian access together with vehicle

movements, a high level of horizontal illuminance is provided. Vertical illuminance from two

opposite directions is also required so that the face of a person approaching from any direction canbe recognised. The appropriate level of illuminance is Category P11 to AS / NZS 1158. Where

disabled car parking spaces are provided the level of illuminance is further increased to Category

P12. The technical parameters for these levels of illumination are listed in section 4.2.3.

The lighting in car parking areas is directed parallel to the marked parking spaces so that the area

between parked vehicles is illuminated, not cast in shadow

Taxi-bays and Bus Terminals

In taxi-bays and bus terminals, it is critical that the passengers are visible to allow them to move

about safely and to avoid accidents between vehicles and passengers.. It is also necessary for

passengers to be able to recognise the correct bus. The appropriate level of illuminance is


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Category P10 to AS / NZS 1158. This provides higher levels of vertical and horizontal illuminance

than those which are required in car parks, where pedestrian movements are less concentrated.

The technical parameters for this level of illumination are listed in section 4.2.3.

Intersections

Uncontrolled intersections should be lit to at least the illumination level required fore the highest

category of the intersecting roads. At least one luminaire should be installed within 10 metres of

the intersection.

At intersections where traffic light signals are installed and intersections where roundabouts are

built lighting should be installed to:

(a) The standard appropriate to the road category; or

(b) Sub-arterial road standard where the road is of sub-arterial or lower category.

Bridges

Bridges should be illuminated to the same level as the roads that approach the bridge.

At locations where the bridge spans are less than the spacing between street lights it will be

structurally convenient to locate lights on each end of the bridge rather than in the centre of the

bridge.

4.2.3 Light technical parameters for each category of lighting

Details of the light technical parameters for each category of lighting are given in AS/NZS

1158.1.1:1997 table 2.1, AS/NZS 1158.3.1:1999 and AS/NZS 1158.4:1987 see Clause 8.4

Australian and New Zealand Standards.

A copy of these standards has been provided to AACRA with this manual.

The relevant requirements quoted from these standards are: -


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Table 4-5 Category VI

For Straight Sections Curves and Intersections

Minimum average carriageway luminance (initial) cd/m2 2

Minimum average carriageway luminance (maintained) cd/m2 1.5

Minimum overall luminance uniformity 0.33

Minimum longitudinal luminance uniformity 0.5

Maximum threshold increment 20%

Minimum surround illuminance ratio 50%

For intersections where the road width changes e.g. due to roundabouts

Minimum Illuminance (initial) (lux) 20

Minimum Illuminance (maintained) (lux) 15

Maximum illuminance uniformity =ratio Maximum/minimum 8

All applications

Maximum upward waste light ratio 6%

At intersections between roads requiring different levels of lighting the higher level shallapply


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Table 4-6 Category V3


Minimum average carriageway luminance (initial) cd/m2 1







Minimum Illuminance (initial) (lux) 10

Minimum Illuminance (maintained) (lux) 7.5


All applications


At intersections between roads requiring different levels of lighting the higher level shallapply


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Table 4-7:- Category V4


Minimum average carriageway luminance (initial) cd/m2 0.75







Minimum Illuminance (initial) (lux) 7.5

Minimum Illuminance (maintained) (lux) 5


All applications


At intersections between roads requiring different levels of lighting the higher level shall apply

Table 4-8 Category P3Maintained Average Horizontal Illuminance (Lux) 1.75

Maintained horizontal illuminance (lux) 0.3

Maintained horizontal illuminance uniformity 10

Maintained vertical illuminance (lux) (applies to pathways not roads) 0.3

Table 4-9 - Category P4

Maintained Average Horizontal Illuminance (Lux) 0.85



At intersections between roads requiring different levels of lighting the higher level shall apply


Maintained Average Horizontal Illuminance (Lux) 35



Maintained vertical illuminance (lux) 17.5


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Maintained horizontal illuminance (lux) 3


Maintained vertical illuminance (lux) 3

Table 4-12:- Category P12


Maintained horizontal illuminance (lux) 7


Maintained vertical illuminance (lux) 7

Supplementary light ing on Pedestrian Crossings

Vertical illuminance not less than 45lx within the specified crossing area

Supplementary light ing on Railway Level Crossings

Best practice is to provide grade separation or gates or boom barriers. Where this is not practical

and where trains operate at night, the crossing should be provided with supplementary illumination

equivalent to a pedestrian crossing. Vertical illuminance not less than 45lx should be provided

within the specified crossing area so that motorists will be able to see a train. Luminaires must be

located so that glare is avoided.

4.3 Lighting Equipment

Lighting equipment must be appropriate to the area in which it is to be used. Modern practice is to

use street lighting luminaires with high pressure sodium vapour, metal halide or mercury vapour

lamps. These offer high efficiency (lumens per watt) and long life, which reduces operating and

lamp maintenance costs. Metal halide lamps are used in areas where excellent colour rendering is

required.

4.3.1 Existing equipment

There are many areas in Addis Ababa where fluorescent and incandescent lamps are still providing

service for low traffic volumes. Because there is a large area of the city with no street lighting it is

likely that some of these will remain in service until age or traffic volumes require their replacement.

However it is recommended that AACRA reviews its operating and maintenance costs.

In many cities it has been found that replacement of these older types of luminaires with new

luminaires containing high pressure sodium vapour or high pressure mercury vapour lamps

reduces the overall cost of street lighting. The longer intervals between lamp replacements and

therefore reduced maintenance costs in many cases more than offset the higher energy costs that

result from increased lamp wattages. In addition the illumination levels are increased.


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4.3.2 Lamps

Lamps are the source of the light for street lighting. In international best practice the desirable

characteristics of lamps for street lighting include: -

(a) High luminous efficacy in terms of lumens output per watt input.

(b) Low whole of life cost. This is a compromise between initial cost, electricity consumption

and lamp life.

(c) Satisfactory colour rendering for the location in which they are used. This may involve a

compromise between best colour rendering and low whole of life cost.

An indicative comparison between the typical performance of various lamps for modern street

lighting can be found in AS/NZS1158.1.3:1997 Table 5.1. This is summarised as follows:

(a) High pressure sodium vapour lamps 100 lm/w, 14000 hour life, fair/ good colour

(b) High pressure mercury vapour lamps 55 lm/w, 12000 hour life, good colour

(c) Low pressure sodium vapour lamps 140 lm/w, 10000 hour life, very poor colour

(d) Metal halide lamps 80 lm/w, 8000 hour life, excellent colour

(e) Fluorescent lamps achieve about 60 lumens per watt and are still widely used in street

lighting applications for the lighting of tunnels.

These comparisons may vary between lamps of different ratings and between lamps from different

manufacturers.

High pressure sodium vapour (SON) lamps are representative of best international practice. They

provide greater economy than either mercury vapour or metal halide lamps and better colourrendering than low pressure sodium vapour lamps. Because of their generally satisfactory and

economical performance and because lamps of this type are already in use in Addis Ababa it is

recommended that high pressure sodium vapour lamps (SON) are adopted as the standard type

for Addis Ababa:

(a) Except where special colour rendering is required and

(b) Until an improved type of lamp is developed.

Where excellent colour rendering is required and in heavily tree lined streets the use of metal

halide lamps is recommended.

The reflectance of the light emitted by high pressure sodium vapour lamps, from green trees is

poor, which causes tree lined streets to appear relatively dark when they are lit by high pressure

sodium lamps.

NOTE: - Metal halide lamps are not internationally standardised at November 2002. There is a

wide range of operating voltages and starting requirements with the result that lamps of the same

wattage are not all compatible with the same ballasts and starting equipment. At present is

preferable, once a small range of metal halide luminaires have been selected, to standardise on

these types to ensure that spare lamps are always compatible with the luminaires that are in

service.


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4.3.3 Luminaires

The function of the luminaire is to protect the lamp and to distribute the light in a controlled manner.

The control gear for the lamp may be housed in the luminare (integral control gear) or in the base

of the pole. For optimum flexibility in mounting, luminaires with integral control gear arerecommended.

The optics of a modern road lighting luminaire are frequently designed to distribute the light in an

asymmetrical pattern that minimises the need to use long outreach arms to place the luminaire

close to the centre of the road.

Figure 4-1 - Typical Horizontal Illumination Distribution

The following types of luminaires are recommended:

(a) Generally complying with a recognised National or International standard, an English

language copy of which must be provided to AACRA...

Note: - The reason for this requirement is to ensure that equipment offered to AACRA has

been manufactured to an acceptable standard and that the basis of tests, which the

manufacturer claims to have carried out can be verified. One example of a recognised

standard is AS3771:1998, a copy of which has been provided to AACRA.

(b) Luminaires for side entry mounting designed for use with high pressure sodium lamps of a

type that require the use of an external ignitron. (These are the type of luminaires

generally used for roadway lighting. Post top lanterns may be required for specific

applications)

(c) Incorporating provision for control of its operation by photoelectric means.

(d) With integral control gear

(e) With power factor correction to 0.9 lagging or better

(f) With blocking inductor

(g) With over current protection cartridge fuse complying with AS 3771:1998 Clause 4.4.3 and

BS1362 or recognised equivalent National or International standard.. (There are two

patterns of cartridge fuses in general use the British pattern and the Continental pattern.

It is anticipated that AACRA may standardise on whichever pattern is more commonly

used in Ethiopia) The reason for specifying fuses in the luminare is to allow the luminare tobe used on poles which have access chambers and circuit breaker or fuses near ground


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level and on poles which do not have this facility. If protection is provided at the base of

the pole, the fuse links in the luminaire may be replaced with solid copper links.

(h) With interference suppression complying with AS/NZS 4051 or recognised equivalent

National or International standard. (It is important that luminaires do not become a source

of excessive electromagnetic interference.

(i) Lamp chamber degree of protection not less than IP 66. (Best international practice now

requires a high degree of protection for the lamp chamber. This minimises the

contamination of the optical system by dust and moisture and extends the intervals

between cleaning. It is expected that luminaires will not need internal cleaning to maintain

satisfactory performance between lamp changes.)

(j) Control gear chamber degree of protection not less than IP 24

Note: - The degree of protection number has basically identical meaning in most national

and international standards for example Australian Standard AS 1939 and British Standard

BS EN 60529 and IEC Standard 529.

(k) Full cut off (aero screen) luminaires are required by ECAA in the vicinity of airports. Full

cut off luminaires may be used of they are otherwise required for particular glare control

requirements in special applications.

(l) Modern luminaires are designed for mounting in a horizontal plane or with a small upcast

angle of approximately 5 degrees. The light output distribution is designed to be controlled

by the optics of the luminaire in conjunction with the mounting position and height. The

use of larger upcast angles in an effort to distribute the illumination across the road will

result in an excessive upward waste light ratio (ULWR). Current luminaire standards

generally specify ULWR < 6% and modern road lighting luminaires frequently achieve lessthan 3% ULWR.

The supplier should be required to provide all of the following information

Photometric Data in hard copy and (if requested by AACRA) in computer readable form.

Evidence of type testing in accordance with recognised standards.

ACCRA may elect to provide to the luminaire supplier:

(a) the relevant combinations of mounting height, overhang, roadway width, arrangement,

spacing and road reserve width nominated in AS3371:1998 clauses 5.5.1 and 5.5.2; or

(b) AACRA may provide details of the road alignment and require the luminaire supplier tonominate suitable luminaires with mounting height, overhang and spacing to achieve the

specified category of illumination. or

(c) AACRA may provide details of the location of existing electrical distribution poles and

require the luminaire supplier to nominate suitable luminaires with mounting height and

overhang to achieve the specified category of illumination. In this case it will be necessary

for EEPCO to agree to the joint use of poles.


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The luminaire manufacturer should be required to carry out all of the tests listed in the

manufacturing standard AS 3777:1998 or in any equivalent standard that may be agreed between

AACRA and the manufacturer.

Luminaire standards also provide for post top luminaires which may become appropriate for the

illumination of areas such as public car parks when these are built in Addis Ababa in the future.

4.3.4 Photocells

Photocells responding to the ambient light level are the preferred method of switching street

lighting. The desirable characteristics are that the lighting is switched ON before full darkness in

the evening and switched OFF in the morning at daylight.

Photocells and the switching device shall be integral with the luminaires.

The photo-sensitive device shall be designed to switch ON the lighting luminaires in the evening at

a daylight level of 20 10% lux and also switch OFF the luminaires in the morning at the same

daylight level.

Lighting will operate all night, nominally from dusk until dawn.

4.3.5 Circuit Breakers and Fuses

A protective device (circuit breaker or fuse) rated to suit the current carrying capacity of the cable

should be installed at each location where there is a reduction in cable size.

Individual circuit breaker (or high rupturing capacity fuse) protection and isolation for the cabling

and luminaire should be provided within the service aperture at the base of each pole. It is

essential that the tripping characteristics of these circuit breakers (or fuses) are chosen to

discriminate with the tripping characteristics of the fuses in each luminaire and with the trippingcharacteristics of the fuses or circuit breakers in the supply pillars.

4.4 Poles

The primary function of poles is to support the luminaires in the correct location whilst being

planted a safe distance from the roadway Refer 4.4.3 Pole Setback. The secondary functions in

international best street lighting practice are:

(a) To provide an enclosure for the cables between the underground cabling and the luminaire

(b) To provide an enclosure above ground level for equipment and earthing.

(c) To provide a cable entry below ground for underground cables.

(d) To provide an aesthetically pleasing appearance.

All of these functions can be provided by hollow concrete or galvanised steel poles suitably

reinforced around the control gear and cable entry openings.

4.4.1 Existing Poles

Existing poles for street lighting in Addis Ababa are rigid poles of 4 main types:

a) Wooden poles (usually pressure impregnated eucalypt species) carrying street lighting

supplied by overhead wiring system. These poles also carry 380 volt and / or 15 kVdistribution systems. It is understood that there is a good pressure impregnation plant


28/98



in Addis Ababa. The slightly green colour of the poles suggests that the treatment may

be copper chrome arsenate impregnation.

b) Concrete poles ranging in length from 8 metre to 14 metre manufactured by EEPCO

carrying street lighting supplied by overhead wiring system. It is understood that

EEPCO has in the past been the only user and the only manufacturer of concretepoles in Ethiopia.

c) Galvanized steel poles (imported) carrying street lighting supplied by underground

wiring system.

d) There are also a small number of steel lattice poles.

4.4.2 Selection of new poles

International best practice currently recognises two types of poles specifically for road or street

lighting in addition to electricity distribution poles which are also used for road lighting.

These two types of dedicated street lighting poles are rigid poles and frangible poles.

Rigid Poles as the name suggests are not designed to break away or yield when struck by a

vehicle. They can be used in locations wherever there is not a high risk of vehicles colliding with

them. Most (or possibly all) of the existing poles in Addis Ababa are rigid poles.

Frangible road light ing polesare designed to break away, yield or otherwise absorb the impact

of an impacting vehicle to the extent that the resultant deceleration forces on the vehicle and its

occupants are reduced to within specified acceptable limits (Source : - AS/NZS 1158.1.3:1997

Appendix B).

Frangible poles are further subdivided into two types:

a) Slip base poles, which are designed to be dislodged from the pole base by a vehicle

impact. These are always used with a plug and socket electrical connection at the

base of the pole so that the electrical supply is automatically disconnected when the

pole is dislodged.

b) Impacts absorbing poles, which are designed to remain attached to the pole base and

absorb impact energy by progressively deforming and trapping the impacting vehicle.

Slip base poles are selected where a secondary accident is unlikely. For this reason they are NOT

the preferred choice where there is high pedestrian activity, where the falling pole could strike aperson walking nearby.

Impact absorbing poles are the preferred choice in areas where there is high pedestrian activity

coupled with the risk of vehicle impacts.

EEPCO is producing and using rigid type of concrete poles for their system. Steel poles for street

lighting system will be more expensive than the concrete poles. Moreover concrete poles are

manufactured and widely used in EEPCO system. AACRA can safely use EEPCO standard

designed and manufactured concrete poles of standard dimensions for their street lighting system.


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Figure 4-2 - Frangible Poles

4.4.3 Pole Setback

The objective of pole setback is to ensure that poles are located far enough from the edge of the

roadway to ensure that the poles will not be struck by vehicles that are outside their designed

carriageway.

The combination of pole setback and the length of the outreach arm (refer section 4.4.6) fixes the

location of the luminaire relative to the edge of the road.

Recommendations are given in AS/NZS 1158.1.3:1997 appendix B for the distance which should

be allowed between the edge of the roadway and the nearest pole. The recommendations for

vehicle speed limits below 70 km/hour are relevant to conditions in Addis Ababa and are

summarised in the tables below.


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In Addis Ababa utility poles such as EEPCO and ETC as well as street light poles are situated in

the road reserves controlled by AACRA, these setback requirements should be applied to all poles

located in the road reserves.

The setback requirements for straight roads are summarised in the following two tables: -

Table 4-13 - Setback Requirement for Roads with Kerbs

STRAIGHT ROADS WITH KERBS AND SPEED LIMIT 0,7 m >3 m >3 mHigh>2.3m 0.7 m >0.7 m >3 m >3 m

< 2.3 m 0.7 m >0,7 m >3 m >3 mLow

>2.3m 0.7 m >0.7 m >0.7 m >0.7 m

Table 4-14:-Setback Requirement for Roads without Kerbs

STRAIGHT ROADS WITHOUT KERBS AND SPEED LIMIT 1 to < 3 m No Poles OK OK >3 mHigh

>3m No Poles OK OK OK

> 1 to < 3 m No Poles OK OK >3 mLow

>3m No Poles OK OK OK

On Curves and Bendsit is recommended that the pole setback should be increased if possible on

the outside of the curve or bend due to the higher accident risk in these locations...

At Intersect ions where the kerb has been built on a radius and extending for 5 metres into the

straight section of the road, the width of the total pole exclusion zone is widened from 0.7 metres to

1 metre outside the kerb.


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At traff ic is lands, medians, spli tters and separators the standard recommends that no pole

should be installed within 6 metres of the end of the structure from which traffic approaches. Note:

- On two way streets and where traffic turns left (in Ethiopia and other left hand drive countries or

turns right in Australia) around the end of the island this requires that no poles be installed within 6

metres of either end of the island, splitter or separator.It is also recommended that no pole should be installed in a splitter island or median less than two

metres wide, except where the median or splitter takes the form of a concrete traffic barrier.

At roundabouts it is recommended that poles should not be installed in the centre of a roundabout

unless the diameter of the roundabout is greater than 6 metres.

Concrete median barrier. Where a pole forms an integral part of a concrete median traffic barrier

setback requirements do not apply. The pole access opening may need to be located higher thannormal to allow access to the interior of the pole.

Guard Fence. Pole setback requirements may be reduced provided that a pole is located behind a

guard fence. The setback distance behind the face of the guard fence should be at least equal to

the designed deflection of the guard fence under traffic impact or 1 metre, whichever is greater.

Figure 4-3 - Poles Setback wi th Respect to Edge of Traffic Lane


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Where the construction of the road does not allow the recommended setback distances for poles to

be observed, the poles should be located as close to the property boundary (i.e. as far from the

traffic lanes of the road) as is possible.

Figure 4-4 - Local Street in Add is Ababa

Figure 4-4shows a street in Addis Ababa. This street provides a convenient example to illustrate

the preferred locations for street lighting poles and any other utility service poles. The preferred

location is on the right hand side of the photograph between the drain and the fence. The drain

provides an effective barrier between the traffic lane and the poles.

The alternative location close to the property boundary fences on the left hand side of the street is

less satisfactory, but is the only other option. The poles on the left hand side are partially protected

from traffic by their proximity to the fence, which deters vehicles from approaching too close. There

are many local streets without drains, kerbs, footpaths or other natural barriers where the onlyposition in which poles can be located is as close as practical to the property boundary fence or

within the structure of the boundary fence.

4.4.4 Pole Construction

International best practice envisages the use of underground cabling and the use of hollow,

galvanized steel or reinforced concrete poles for street lighting with provision for the following

facilities:

a) Cable entry below ground level for the entry of underground cabling.


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Table 4-15:- Recommended planting depths for rigid poles and pole foundations

Hole depth Pole length m Pole height above ground

0.1 H +K where K=1 H 0.9H-K

-1.8 8 6.2

-1.9 9 7.1

-2 10 8

-2.1 11 8.9

-2.2 12 9.8

-2.4 14 11.6

There is an additional requirement where poles are to be located in swampy ground or ground that

has low bearing strength for a concrete foundation to be provided to the approval of the AACRA

Engineer for Contract.

It is not known whether or not EEPCO has the production capacity, in excess of its own

requirements to build poles for AACRA requirements.

It is understood that EEPCO has the technology to provide earthing connections inside the pole.

AACRA will require this.. No EEPCO concrete poles with side openings for cable entry, equipment

compartments above ground level or openings for cables to luminaires have been observed. The

concrete construction technology would normally permit these features to be provided, with

appropriate reinforcement around the openings, if required. It is recommended that AACRA should

consider negotiating with EEPCO to have street lighting poles built to AACRA requirements.

AACRA requirements will include: -

a) Cable access openings below ground similar to those shown on the EEPCO

standard drawing in Section 7. The edges of both cable and equipment access

openings must be suitably reinforced to maintain the strength of the pole.

b) Equipment access door above ground. The door frame should be cast into the pole.

The door should be hinged on one side and locked to the frame on the other side with

suitably lubricated, captive, tamper resistant screws or an agreed locking device. (A

special tool will be required to remove these screws.) The door should be attached to

the frame with a high tensile wire cable to limit the opening angle to approximately 120degrees and to resist theft of the door. The corners of door openings must be radiused

to reduce stress concentrations. The door should be made of hot-dipped galvanized

steel or other corrosion resistant material.

c) Equipment mounting plate inside the pole behind the door. For mounting a circuit

breaker (or high rupturing capacity fuse) for each light together with cable anchors,

terminal blocks and earthing terminal.

d) Earthing conductor from top to bottom with facilities for connecting to the outreach arm

at the top and to the earthing terminal on the equipment mounting plate.


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e) Facilities as agreed between AACRA and EEPCO for attaching the outreach arm(s) to

the top of the pole.

f) Straightness of poles should be within 3mm per metre of length.

g) Permanently marked identification located at a height of approximately 2 metre aboveground level. This should include manufacturers identification, year of manufacture,

pole length in metres, mass in kilograms, and load capacity in kilonewtons. This

information may be fixed to the pole as a plate with the information in full or as a

barcode. Bar coded information may assist AACRA to enter pole details into the

AACRA Pavement Maintenance and Bridge Management System.

The above requirements include information extracted from AS/NZS 4065:2000 which describes

requirements for Concrete Utility Services Poles. A copy of this standard was handed over to

AACRA.

Figure 4-5 - Pole with Integral Outreach Arm


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Figure 4-6 - Reinforced Spun Concrete Poles Used for Street Lighting

Note the equipment access door facing the camera approximately one metre above ground level.

The outreach arms supporting the luminaires at the top of the pole are metal.


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Pole without Pole with detachable

outreach arm outreach arm

Figure 4-7: Standard Pole Details


38/98



Door Opening Detail Cable Entry Detail

for Fuse Board for Buried Cable

Figure 4-8: Opening & Entry Details

Door opening dimensions, mmItem No. Nominal mounting Height, Hn, m

a b

Pole with outreach arms

1 Hn7.5 60 300

2 Hn>7.5 130 400

Pole without outreach arms

1 Hn5.5 60 300

2 Hn>5.5 130 400

4.4.6 Outreach arms

Outreach arms allow the pole to be set back at a safe distance away from the roadway whilst the

luminaire is positioned closer to the centre of the roadway so that the optimum distribution of light

on the roadway can be achieved. The range of outreach arm lengths required for optimumpositioning of luminaires are likely to range between 1metre and 6 metre for the road widths which

are used in Addis Ababa.. The recommended uplift is (uplift = 0.5 x outreach) up to a maximum of

2 metres uplift for outreach arm projections > 4 metre. The recommended spigot angle is 5

degrees except where an angle of zero is required to meet upward waste lighting limits in the

vicinity of airports refer 2.4.1.

4.4.7 Computer Programs, Pole Spacing and Lighting Performance

Pole spacing depends on the requirements for illumination level and uniformity and on the light

distribution and lamp output for the type of luminaire being used. The most accurate way to

determine pole spacing is to use a computer program.


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With any request for quotation to supply luminaires, the supplier of the luminaires can be required

to supply details of optimum mounting heights, outreach arm lengths and pole spacings to satisfy

the illumination requirements nominated by AACRA.

Pole spacings must be varied slightly to accommodate the positions of existing building entrances

and street intersections. Computer designed lighting layouts may be able to achieve pole spacingsup to seven times the luminaire mounting height on straight sections of road before adjustments

are made for the locations of intersections.

Computer programs can be used by ACCRA to determine pole spacings based on the required

illumination levels (lighting performance) and road widths together with standard pole heights and

outreach arms.

Most luminaire manufacturers can supply luminaire data in a form to suit the design program being

used by AACRA and / or supply their own proprietary software to suit their luminaires. They will

usually undertake the software calculations when they are quoting to supply luminaires.

Perfect Lite software can be supplied by Trevor Caswell Software, refer 8.7.7

Reality Real Time lighting design software can be supplied by Lighting Reality, Somerville House,

Harborne Rd., Birmingham B15 3AA England, refer 8.7.8

Fael Luce lighting design software will be supplied by this manufacturer, usually free of charge, on

request, refer 8.7.9

Computer predictions of performance are sufficiently accurate to determine whether or not a

proposed installation will meet the specified requirements. A copy of Australian / New Zealand

Standard AS / NZS 3827:1998 Lighting System Performance, which provides a guide to the

accuracy of the lighting performance that can be expected from computer predictions of street

lighting performance and the methods of verifying the design was handed over to AACRA.

4.5 Lighting Design Submission

All lighting designs must be submitted to AACRA for approval.

The submissions must include the following technical information: -

a) Comparison of any Standards proposed by the Designer with the Standards specified

by AACRA.

b) Lighting layout plan and relevant cross sectional drawings

c) Circuit diagrams and electrical; schematic wiring diagrams

d) Specification and description of the lighting scheme and of the individual items of

equipment offered.

e) Design parameters and criteria.

f) Calculations of : -

i. Minimum average carriageway luminance (initial)

ii. Minimum average carriageway luminance (maintained)

iii. Minimum overall luminance uniformity

iv. Minimum longitudinal luminance uniformity


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v. Maximum threshold increment

vi. Minimum surround illuminance ratio

vii. Maximum upward waste light ratio

viii. Minimum illuminance at intersections and junctions (initial)

ix. Minimum illuminance at intersections and junctions (maintained)

x. Maximum illuminance uniformity ratio (E max /E min) at intersections and junctions

4.6 Installation

4.6.1 Poles

Poles shall be installed in locations as indicated in the approved drawings or as advised by

AACRA. The poles shall be located at a safer distance far enough from the edge of the roadway in

order to protect the poles from the vehicular movement. In case the poles can not be located insafer places strong metal guard fence as shown in the Standard Bridge Manual drawings (Nos. GR

01 to GR 09) shall be erected on the roadside of the poles to absorb the shock when the poles

will be struck by any vehicle while jumping the road kerbs at the designated speed of the

motorway.

Poles should be mounted for true vertical alignment (+/- 0.5 degree). Direct buried poles should be

installed to the standard depth appropriate to the length of pole.

Provision must be made for cable entry into the base of the pole and for earthing before backfilling.

Flange mounted poles are to be provided with a concrete plinth with the base flange oriented so

that the pole outreach arm will be perpendicular to the roadway.

Poles are tall slender structures designed to stand vertically. They are relatively easy to damage

whilst being transported and handled horizontally. Concrete poles in particular are brittle and easily

broken if they are dropped. All poles must be carefully and evenly supported during lifting, storage,

transport and erection. Webbing slings should be used in preference to wire ropes or chains for

lifting poles.

The poles to be used shall be of standard EEPCO concrete poles of different heights and

dimensions. The planting depth of the different types of poles are shown in Table 4-15.

4.6.2 Ducts and Pits

Ducts and pits are required for the installation of street lighting cables and also for:

a) Traffic signal cables

b) Power distribution cables

c) High voltage distribution cables

d) Telecommunication cables

Facilities are also required for water and drainage pipe as shown in concept sketches in the Addis

Ababa City Road Network (final draft) April 2002 section of the master plan.


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Future provision will also be required for sewerage collection and future provision may be required

for gas distribution pipe work.

In locations where all of these services are required, they can be enclosed in a common trench

provided that sufficient separation is maintained especially between telecommunication and other

electrical services.

In locations where street light cables are installed separately from other services they should be

installed in rigid circular polyvinylchloride duct. The recommended minimum diameter for street

lighting cable ducts is 100 mm. Heavy duty electrical conduit to Australian Standard 2053 is one of

the suitable specifications for cable duct. (Suppliers may offer alternative specifications subject to

the approval of the AACRA Engineer for Contract.)

The duct should preferably be coloured orange to distinguish it from other non-electrical services.

The duct must be not less than 600 mm deep under footpaths and not less than 1 metre deep

under roadways to avoid adverse effects on the structural integrity of the road pavement and to

afford protection to the buried cables from damage due to traffic loadings or subsequent roadopening works.

The duct must be bedded in compacted sand to prevent damage to the duct. A continuous marker

tape bearing the words ELECTRIC CABLE in Amharic and in English at intervals of approximately

1 metre must be laid approximately 100 mm above the duct to identify the location when future

excavations are in progress. Duct marker block must be installed on either ends of the ducts

installations.

Note: - Marker tape is not required in the case of bored ducting or conduit under existing roadways.

Ducts must be provided with 4mm diameter polypropylene draw rope to assist the pulling in of

cables. Rope must have a minimum of 1.5 metres of slack in each pit and must be firmly securedto prevent the ends from being lost in the duct.

Pits are required to assist with cable pulling in any straight run of duct exceeding 100 metres in

length and at every abrupt change in direction or level of the duct irrespective of length.

A pit is also required at each location of a cable joint to provide a space for the jointing work to be

carried out. Alternatively cables may be joined at the terminal point in each pole.

Pits must be large enough to allow the cable pulling and cable jointing work to be carried out. The

recommended sizes are shown in the following table.

Table 4-16:-Recommended minimum internal dimensions of pits (metre)

Depth of cable duct below ground surface Depth of pit Length of pit Width of pit

1 metre 1.2 1.2 0.8

600 millimetre 0.8 0.8 0.8

Precast pits must be bedded in compacted sand. All pits must be provided with drainage holes in

the bottom. The lowest pit in any run of duct should be bedded on a filter material to prevent

vermin from entering the pit. The filter material should be provided with a free draining connection

to the nearest drain.


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4.6.3 Earthing

The neutral conductor of the street lighting circuit together with accessible metal parts of the

luminaire body and the pole must be earthed at every pole.

The earth resistance at each point on a street lighting circuit must be low enough to cause thecircuit protection to operate rapidly when there is an earth fault on the circuit. For rapid tripping the

prospective fault current should be about 4 times the nominal rated current of a circuit breaker (or

fuse). For a 220 volt circuit with a 16 amp circuit breaker the tripping current for rapid fault

clearance should be about 64 amps which require an effective resistance to earth of approximately

3.4 ohms.

Provided that the neutral conductor is earthed at the supply pillar and at each pole, the resistance

to earth at each pole is made up of the resistance to earth of the electrode at that pole in

conjunction with the effective resistance at that pole of all other pole and pillar earths on the same

circuit.

Figure 4-9 - Components of Effective Resistance

The effective resistance to earth at each supply pillar and at each pole should be measured after

installation is complete. If necessary additional earth stakes should be driven adjacent to any pole

where the resistance is not low enough OR additional bare copper conductors may be laid in the

trench near the cable duct and connected to the earth electrode and the neutral conductor at each

pole.

The resistance of a single driven rod electrode may be estimated as:

Rg= (/2L)[ln{8L/d}-1] ohms

R Earth R Earth R Earth R Earth R Earth

R neutral R neutral R neutral R neutral R neutral


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Where Rg= resistance of the driven electrode to earth (ohms)

= resistivity of soil (ohm metre)

= 3.14159

ln = natural logarithm

L = length of driven earth rod (metres)

d = diameter of driven earth rod (metres)

Where a rigid concrete pole is to be direct buried a copper rod of not less than 12 mm diameter and

length equal to the depth of burial of the pole must be fixed to the outside of the buried section of

the pole and connected to the neutral terminal inside the pole before the pole excavation is

backfilled.

Where a steel pole is to be provided with a reinforced concrete foundation the reinforcing within the

foundation will form the earth electrode. The reinforcing must be connected to the pole where the

pole is direct buried or welded to the fixed flange or the anchor bolts, which will anchor the pole to

the base. The neutral terminal must then be connected to the anchor bolt or flange.

Where a pole is mounted on a bridge an earthing electrode can not usually be established. In this

case an earthing conductor must be run through the service duct to the nearest pole at which there

is an earthing electrode.

The copper conductor connecting the neutral terminal to the earth electrode must be not less than

16 sq. mm in cross sectional area.

4.6.4 Supply Pillar (Feeder Pillar)

Street lighting power supply pillars are required to house the following equipment at supply point

locations agreed with EEPCO.

a) EEPCO incoming supply cable termination.

b) EEPCO main isolating switch.

c) EEPCO incoming supply meter. (Note: - in some areas an un-metered tariff based on the

number and type of luminaires connected and the average burning hours per year is

negotiated.)

d) AACRA main isolating switch.

e) AACRA street lighting distribution board complete with 3 phase 4 wire combined residualcurrent device / circuit breakers with 500 milliamp earth leakage protection for each

outgoing circuit.

f) Earth Link.

g) Neutral Link.

h) AACRA outgoing street lighting cable terminations. Outgoing circuits may also supply

power to traffic light signals.

Supply pillars should be lockable and constructed of heavy gauge galvanised steel with enclosure

degree of protection IP 44.


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Equipment mounting panels inside supply pillars should be galvanised steel or of a non-

hygroscopic rigid non-biodegradable insulating material. Wood and wood products should not be

used. Equipment mounting holes should be neatly drilled.

If it is necessary for wiring to pass through metal panels the holes should be bushed so that there

are no sharp edges. Equipment mounted on the panels should preferably be all front connected orall back connected so that it is not necessary for wiring to pass through panels.

Wiring inside supply pillars should be neatly laid in PVC or metal ducting with close fitting lids.

Each supply pillar should be provided with a removable gland plate at the bottom for cable entry.

Every cable entering a supply pillar should pass through a close fitting gland.

Supply pillars should preferably be mounted on a concrete plinth with provision for entry of cables

and with provision of an earth electrode. If necessary pole mounted supply pillars may be used.

The upper surface of the concrete plinth on which any supply pillar is mounted should always be

above the level of any foreseeable flood.

The earth electrode at each supply pillar should achieve a resistance to remote earth less than 5

ohms before interconnection to pole earths in outgoing circuits.

The Supply Pillars shall be installed at safer locations on road sides with additional protection by

guard fence as shown in the Standard Bridge Manual drawings (Nos. GR 01 to GR 09)

A standard sample of Steel Cabinet Supply Pillar with incoming and outgoing modules is shown in

the following figure.

Figure 4

aacra street lighting manual

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