Memorandum submitted by the Institution of Public Lighting Engineers






1.1                   The Institution of Public Lighting Engineers (IPLE) is pleased to learn of the Select Committee's inquiry into road safety and welcomes the opportunity to submit evidence in support of measures to improve safety to all road users during the hours of darkness.


1.2                   The IPLE was formerly the Association of Public Lighting Engineers, founded in 1924. IPLE is affiliated to the Council of Engineering Institutions and is the sole professional body representing those engineers engaged in the provision of public lighting in the external environment.


                        The membership of IPLE is international and includes chartered engineers, scientists and physicists representing the various lighting interests of local authorities, manufacturers and national associations.


1.3                   The opinions and recommendations expressed hereafter represent the views of an Institution solely and totally committed to the provision and improvement of lighting in the external environment as a service amenity giving assurance and safety to members of the public during the hours of darkness.


1.4                   The technical expertise developed by the multi-disciplined Engineers within the Institution includes full knowledge of the production and distribution of light to reveal the presence and movement of objects to all road users and thereby to promote night-time safety.




2.1                   Road Lighting


                        Perception of a visual scene depends upon contrasts of light and shade or of colour. At road lighting levels, colour contrasts are rarely perceptible, so it is necessary to rely upon luminance (brightness) contrast.                   


2.2                   Luminance contrast may be positive or negative i.e. an object, or part of an object, may appear brighter or darker than its immediate background. Against bright road surfaces or surroundings, objects are in general, revealed by negative contrast, or silhouette.


2.3                   The object of fixed road lighting is, therefore, to provide a uniformly bright carriageway and to direct adequate light to the immediate surroundings, either to produce a bright background or, if this is absent, to reveal objects by positive contrast.



2.4                   Glare


                        Particular care is also taken to restrict glare by severe limitation of light intensities emitted from the fixed lanterns in directions approaching the horizontal.


2.5                   DisabilityGlare


                        Disability Glare is a physical factor caused by the light entering the eye directly from sources within the field of view, creating a Veiling Luminance over the retina, which reduces the perception of any luminance contrast between an object and its background. A simple experiment will demonstrate that this Veiling Luminance is practically instantaneous in its effect and is a physical reality from which no one is immune.


2.6                   Headlights


                        On an unlit road a driver has to use headlights whereby objects are seen mainly by positive contrast.


2.7                   Dipped Headlights


                        If dipped headlights are correctly adjusted, they are adequate for driving at reasonably high speeds on unlit roads by similar dipped headlights on opposing vehicles.


2.8                   On well lit roads, drivers know from experience that switching on their own dipped headlights rarely assists them in seeing objects ahead. The reason for this is that the fixed road lighting reveals objects primarily by negative contrast, which is counteracted by dipped headlights which promote positive contrast. This inevitably means that disability glare from opposing dipped headlights is very much more severe than on unlit roads when all vehicles use dipped headlights.


2.9                   An appropriate reduction in the power of dipped headlights to overcome this disadvantage, would of course, render them inadequate for high speed driving on unlit roads.


2.10                 For this reason the Secretary of State for Transport, proposes to make Regulations requiring motor vehicles to be fitted with DIM-DIP LIGHTING DEVICE, which can be manually operated by the driver and this proposal is strongly supported by the Institution.


2.11                 This device would automatically switch on the headlights with DIM-DIP BEAMS when the sidelights are switched on whilst the engine is running. This would make it impossible to drive using only side-lights and drivers would be free to use DIM-DIP or DIPPED HEADLIGHTS on any road, regardless of the quality of the final road lighting.


2.12                 Drivers would appreciate the good sense of having this discretion available to them and would act appropriately, just as they use FULL or DIPPED HEADLIGHTS, on unlit roads. There would also be no objections to making legislation enforcing the use of at least DIPPED or DIM-DIP LIGHTS at all times during the hours of darkness.




3.1                   In 1963 a dipped headlight campaign was launched for a limited period in Birmingham and this repeated in the following year in Birmingham and four other large towns.


3.2                   The accident records recorded for those towns operating dipped headlights campaigns, were compared with six similarly sized towns not holding similar campaigns. The analysis of the data obtained led to the conclusion that, "the usage of dipped headlights had a negligible effect on total causalities during the dark hours", and in campaign towns, other than Birmingham, "there was some evidence of an adverse effect on total casualties during the hours of darkness".


3.3                   The overall conclusion relating to dipped headlight usage was "the only significant change found which can be associated with the use of dipped headlights at night, was the reduction of pedestrian accidents on less well-lit roads, but dipped headlights have no benefit and may even be harmful on well-lit roads". (Refer RRL Report LR 210-1968, "Some Further Data relating to the Dipped Headlights Campaign in Birmingham and other towns").


3.4                   The provision of DIM-DIP LIGHTING DEVICES is estimated to be below 4.


3.5                   The Institution is convened to see in the popular press that there is opposition to the DIM-DIP proposals from areas of vested interest because they consider the proposal to be a barrier to trade.


3.6                   It is the strongly held view of the Institution as a professional body responsible for the improvement of the science of lighting on roads, that the use of vehicle DIPPED HEADLIGHTS on well lit roads is not appropriate because of discomfort glare and dazzle which reduces the effectiveness of vision to the danger of the pedestrian and the driver.


3.7                   In the absence of a better system it is understandable that the drivers have adopted the wide use of the DIPPED BEAM in well lit streets to try to improve pedestrian and vehicle conspicuity.


3.8                   It is important to note that France, on the 15th October 1979, made the use of dipped headlights in built-up areas compulsory. However, as the compulsory use of dipped headlights HAD NOT RESULTED IN ANY SIGNIFICANT CHANGES and, following protests from motorists and road users in general, on the 19th December 1981, the Interdepartmental Committee on Road Safety, comprising of the Home Secretary, the Minister of Transport and the Deputy to the Minister for Leisure Activities and chaired by the Prime Minister, REVOKED THE COMPULSORY USE OF DIPPED HEADLIGHTS IN BUILT-UP AREAS IN FRANCE.


3.9                   The French Medical Automobile Association had conducted a survey of dipped headlight usage and found that out of 204 responses by doctors, 56 per cent opposed the use of dipped headlights on lighted roads caused medical effects which were contrary to road safety.


3.10                 The responses against the use of dipped headlights included four from Ophthalmologists, including a Professor of the Paris Faculty of Medicine, and the President of Practising Opthalmologists. Some 81 per cent of the French medical profession were against the compulsory use of dipped headlights in built-up areas.


4.                     PUBLIC LIGHTING AND ROAD SAFETY


4.1                   In this country the number of night-time accidents (including nonfatal accidents) for related travelling distances, is approximately 1.8 times that by daytime. Studies in many countries carried out by various institutions, have shown conclusively that good road lighting can help to reduce the number of night-time accident by more than 30%. The majority of these studies relate to night-time accidents before and after the provision of upgrading of lighting is made.


4.2                   There is simple evidence to indicate that improved lighting of roads leads to an appreciable reduction in accidents at night. Studies show reductions of 30 to 45 per cent for urban roads, 19 to 48 per cent for rural roads, and 16 to 55 per cent for motorways. Additionally, the proportion of fatal and serious accident occurring at night, is reduced.


4.3                   Investigations on the use of sidelights and dipped headlights in built-up areas, were the subject of a Report issued in 1969 by the Institute for Road Safety Research, SWOV, The Netherlands. The Report concluded that the glare caused by approaching cars headlights with European dipped headlight or E beam, is unacceptably serious on well-lit roads, especially if there are a large number of approaching vehicles, and sidelights hardly ever cause glare but in many cases are not conspicuous enough. The Report recommended that is was advisable to seek a lighting system for the front of vehicles with a light intensity between the present dipped headlights and sidelights, and guaranteeing adequate conspicuousness.


4.4                   A similar study was carried out by A J Fisher while at the Department of Transportation and Environmental Planning, University of Birmingham, the work being supported by the Science Research Council. The road research group S2 of the Organisation for Economic Co-operation and Development (OCED) had identified the question of the use of headlights in street lighting as one requiring research and international co-operation.   


4.5                   Previous studies by the Roads Research Laboratory and the Institute for Road Safety Research (SWOV) indicted that it was undesirable to require that dipped headlights be used at all times in order to secure their use on unlit or poorly lit streets, while accepting that present sidelights were adequate.


4.6                   A series of tests were carried out to establish the luminous requirements of a vehicle front light that is adequately conspicuous without being glaring. The report published in 1974 recommended that the optimum lighting from vehicle front lights should be a town beam based on dimming the present dipped headlights to an intensity straight ahead of 80- candelas.


4.7                   The Joint Committee of CIE (International Commission on Illumination) issued the following statement in 1975 recognising the problem and the research work carried out. "It is recommended that a town beam be introduced which is intermediate in intensity between the currently used low beam and sidelights. Such a beam should have a luminous intensity between 50 and 100 candelas and have an area similar to that of the current headlights".


4.8                   The Road Research Laboratory had presented Report LR66 in 1967 which included reference to the examination and possible introduction of dimmed headlight systems with details of the London postal region headlight experiment on G.P.O. vehicles. This report concluded that the system was reliable and could have possibly contributed to a reduction in night-time accidents.


4.9                   The Transport and Research Laboratory conducted further study on the use of automatic headlight dimming systems and further to trials on Police and G.P.O. vehicles, a Report 880 was issued in 1979 entitled "Town Beams for Vehicles - Experience with an Automatic Headlight Dimming System". The Report concluded that the automatic system was unacceptable and future work should be directed towards a safety assessment of the manual system.


5.                     RECOMMENDATIONS


5.1                   In conclusion, the IPLE in considering the foregoing submission, in cognisance of matters relating to the external night-time environment, the relevance to light and the physiological responses of the human eye, the cost-effectiveness of fixed road lighting systems, the need to ensure the safety of all road users, the inadequacy of sidelights for vehicles in motion and the overall need to present a situation in which reasonable legal enforcement can be made, make the following recommendations to the Transport Committee for consideration.


5.2                   Road Lighting


5.2.1                To provide encouragement to Local Authorities to the installation or upgrading of road lighting on all urban roads to conform with the British Standards Institution Code of Practice for Road Lighting, CP 5489: 1974 or subsequent revision thereof.


5.2.2                To consider financial assistance to Local Authorities to upgrade and modernise road lighting installations to improve efficiency and reduce maintenance costs.


5.3                   Vehicle Lights


5.3.1                To enforce the mandatory fitting of Dim-Dip lighting of the recommended type to all new vehicles at an appropriate date.


5.3.2                To promote the development of devices incorporating economic electric circuitry similar to that proposed by the Secretary of State for Transport, of existing vehicles to be converted to the recommended dim-dipped type.


5.3.3                To encourage Industry to carry out research into improved vehicle lighting systems.


5.3.4                To encourage the use of dim-dipped headlights on well lit roads.


5.3.5                To seek improved legislation to ensure correct setting of vehicle lights in the M.O.T. tests and that random roadside checks are carried out.


6.                     APPENDIX


6.1                   The London Postal Region Headlight Experiment. V J Jehu. RRL Report LR66 1967.


6.2                   Some further factors relating to the Dipped Headlights Campaign in Birmingham and other Towns. A W Christie and R F Newby, RRL Report LR 210, 1968.


6.3                   Side lights and Low Beam Headlights in Built-Up areas. Institute for Road Safety Research SWOV, The Netherlands, 1969.


6.4                   Lighting, Visibility and Accidents. Organisation for economic Co-operation and Development, OCED, 1971.


6.5                   The Luminous Intensity Requirements of Vehicle Front Lights for use in Towns. A J Fisher, School of Transportation and Traffic, New South Wales, Ergonomics 1974. Vol 17, No. 1, 87-103, 1974.


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