1、 CIE 93 cf2 m 900bL45 O004287 94T ISBN 3 900 734 305 COMMISSION INTERNATIONALE DE LCLAIRAGE INTERNATIONAL COMMISSION ON ILLUMINATION INTERNATIONALE BELEUCHTUNGSKOMMISSION ROAD LIGHTING AS AN ACCIDENT COU NTERM EASU RE Pub. No. CIE 93 1st Edition 1992 UDC: 628.971.6 Descriptor: Street lighting _ - CI
2、E 93 92 9006145 0004288 886 II This Technical Report has been prepared by CIE Technical Committee 4-02 of Division 4 Lighting and Signalling for Transport and has been approved by the Board of Administration of the Commission Internationale de IEclairage for study and application. The document repor
3、ts on current knowledge and experience within the specific field of light and lighting described, and is intended to be used by the CIE membership and other interested parties. It should be noted, however, that the status of this document is advisoq and not mandatory. The latest CIE proceedings or C
4、IE NEWS should be consulted regarding possible subsequent amendments. Ce rapport technique a t prpar par le Comit Technique CIE 4-02 de la Division 4 Eclairage et signalisation pour les transports et a t approuv par le Bureau dadministration de la Commission Internationale de IEclairage, pour tude e
5、t application. Le document traite des connaissances courantes et de lexprience dans le domaine spCifique indiqu de la lumire et de lclairage, et il est tabli pour lusage des membres de la CIE et autres groupements intresss. Il faut cependant noter que ce document est indicatif et non obligatoire. Po
6、ur connaitre dventuels amendements, consulter les plus rcents comptes rendus de la CIE ou le CIE NEWS. Dieser Technische Bericht ist vom CIE-Technischen Komitee 4-02 der Division 4 Beleuchtung und Signale fr den Verkehr ausgearbeitet und vom Vorstand der Commission Internationale de IEclairage gebil
7、ligt worden. Das Dokument berichtet ber den derzeitigen Stand des Wissens und Erfahrung in dem behandelten Gebiet von Licht und Beleuchtung; es ist zur Verwendung durch CIE-Mitglieder und durch andere Interessierte bestimmt. Es sollte jedoch beachtet werden, da das Dokument eine Empfehlung und keine
8、 Vorschrift ist. Die neuesten CIE-Tagungsberichte oder das CIE NEWS sollten im Hinblick auf mgliche sptere nderungen zu Rate gezogen werden. Any mention of organisations or products does not imply endorsement by the CIE. Whilst every care has been taken in the compilation of any lists, up to the tim
9、e of going to press, these may not be comprehensive. Toute mention dorganisme ou de produit nimplique pas une prfrence de la CIE. Malgr le soin apport Zi la compilation de tous les documents jusqu la mise sous presse, ce travail ne saurait Engineering, Education and Enforcement. Countermeasures are
10、related to the three compo- nents of the road transport system, viz: the road users the vehicles the road environment and to primary (accident prevention) or secondary (trauma reduction and treatment) safety by the formal road safety matrix shown in Fig 2.1. Road lighting is a potential engineering
11、measure operating in the context of road environment/accident prevention. Fig 2.1: Matrix for road accident and countermeasure evaluation. Note: Only the cell relating to the consideration of road lighting is indicated. Countermeasures which can be engineered into the road environment and vehicles r
12、equire little or no conscious cooperation of the road user for their success, and they are seif-enforcing . As the transportation system is complex, a more sizeable reduction of road accidents may be expected when a number of countermeasures are involved in a safety program. Which measures are used
13、will depend on their relevance to the particular accident situation, their proven effectiveness and the ratio of the benefits accruing to the costs of implementation. It is within this framework that road lighting as an accident countermeasure is examined. CIE 93 92 B 6 2.3 ROAD ACCIDENTS AT NIGHT I
14、t is difficult from a cursory examination of accident data to isolate the effect and responsibility of darkness alone on road accidents. However the data lead to the incontrovertible conclusion that the accident problem during the hours of darkness is worse than in daylight. A compre- hensive survey
15、 of road safety at night has been made by the Organisation for Economic Co-operation and Development 64; much of the data presented in this section is taken from that report. A disproportionately large number of accidents and resultant casualties occur during the hours of darkness. By disproportiona
16、tely large is meant large in relation to the exposure of road users in the road transport system, measured by the number of vehicle kilometres or person kilometres travelled in the hours of darkness. The number of fatalities occurring at night is likely to approach that by day. The proportion of fat
17、al accidents occurring at night in 13 OECD countries range between 25 and 59 per cent, with a median value of 48,5 per cent a. However, estimates of vehicle kilometres travelled during the hours of darkness range from 17 to 32 per cent. Therefore, in general, the casualty accident rate during the ho
18、urs of darkness will be several times that for the hours of light; at weekends this difference is further accentuated: see Fig 2.2. Re1.R ate 5 2 1 0.5 I O 12 24 1 time Fig 2.2: Relative accidental fate with time of day, where 7 is the average rate throughout the day (Mer OECD, ref 64). Accidents ai
19、 night are generally more severe in their consequences and more likely to produce fatalities and severe personal injuries than by day 65. Accidents involving multiple vehicles and pedestrians increase in severity, This increased seventy is reflected in the greater economic cost of accidents ai night
20、 1661. CIE 93 92 900bL45 0004301 4T 7 This pattern of increased accident rate and accident severity at night applies not oniy to urban traffic routes but to the whole hierarchy of roads - rural roads (despite pedestrians being largely absent) and freeways (in spite of superior design). The distribut
21、ion of accidents within the road system of a country will reflect the degree of urbanisation within that country and the usage of the road system. In general a larger proportion of accidents will occur in urban areas than in rural areas; in urban areas accidents involving pedestrians may predominate
22、 whereas in rural areas single vehicle ones may do so. Along many roads there is some form of lighting and here the concern in this report is for the beneficial effects of upgrading lighting and disbenefits from the down grading and switching out of lighting. In most countries the majority of urban
23、roads and only a proportion of main rural roads are lit. However, the lighting of rural roads should be considered since a significant proportion of total night fatalities can occur on rural roads 67. The absolute volume of traffic is in general growing with time. The absolute number of accidents, h
24、owever, has decreased in most countries since the early seventies. It is not clear whether the proportion of the casualties occurring at night or the night accident rate, relative to the day rate are increasing with time 68. However, data from five OECD countries suggest there is no marked trend, ei
25、ther increasing or decreasing MI. What is evident is that the night accident problem is not going to disappear and hence it is still most important to consider road lighting as an accident countermeasure. 2.4 FACTORS INFLUENCING NIGHT ACCIDENTS It is generally recognised that a single causal factor
26、cannot be assigned to accidents. WhUe the majority of accidents have an element of human error or failing, this is usually found to be in combination with problems of road design and adverse weather conditions. Reduction in visibility, due to darkness, is intuitively a major factor in the increased
27、accident problem at night. However, the non-visual factors wilt also contribute and one may expect adverse interactions between darkness and these factors. It is to be expected that properly designed, installed and maintained lighting will increase visibility and also combat these other causal inter
28、actions to some extent. 2.4.1 Light and vision Nearly all of the information that the road user needs in order to drive, ride or walk effectively is of a visual nature. At night such information is often less perceptible and consequently the road user will be less efficient than during the day. As t
29、he light level falls, visual performance deteriorates: visual acuity, contrast sensitivity, distance judgement, speed of seeing, colour discrimination, and glare tolerance are all impaired 69. Some visual information consisting of self luminous sources, such as traffic signals, will be made more con
30、spicuous by darkness and easier to see. Other information, the conspicuity of which depends on reflected light, will be more difficult to see, such as the extent of the visual field and details in it that aid the driver in making subtle judgements of position, speed and trajectory of his vehicle. Su
31、ch judgements, therefore, will be more difficult, and take more time to make. In an extreme case an object or a pedestrian will not be seen by a driver at all, or until it is too late to avoid. Experimental evidence suggests that modest levels of lighting, far lower than daylight, will be satisfacto
32、ry for effective performance by the road user at night. For some roadway situations, particularly low traffic volume rural roads, retroreflective delineation may be sufficient to provide the driver with the necessary visual information. However, as the road becomes busier and more complex, vehicle h
33、eadlights cannot provide the degree of information needed. This arises because of the need to limit glare from headlights from the geometry of vehicular lighting systems, and from the location of information required by road users. For higher driving speeds, the reach of dipped beam headlights is in
34、sufficient for the detection of objects on or near the road as drivers need more information about what is happening further along the road and off to the sides where headlights do not penetrate. Road lighting can provide the necessary visual conditions to overcome these limitations. From studies of
35、 the visual processes involved in acquiring visual information from the road scene, it has been shown that the visibility of an object is dependent primarily on the light 8 level and also on lighting uniformity and glare restriction 70. Methods have been developed in which thevisibility of standard
36、objects within an installation can be computed and the visibility performance potential of a lighting installation can be assessed 71 J. Gallagher 72 reported on the reactions of unsuspecting motorists to an object placed on a low volume urban street. He found that the time remaining to collision at
37、 the moment the drivers reacted, assuming no changes in vehicle velocity, increased with increasing conspi- cuity of the object, measured on a Visibility Index (Vi). The time to collision increased with increasing road luminance until after a certain level there was no further improvement. The relev
38、ance and application of these matters to current practical lighting design is discussed elsewhere 73. 2.4.2 Non-vlsual factors Factors other than light level and visibility contribute to the increased night accident rate. These include fatigue, intoxication, changes in road user population, traffic
39、flow and weather condi- tions. These can adversely interact with darkness. 2.4.2.1 Fatigue As a result of normal activity patterns, people are usually more fatigued at night than during the day. Whilst fatigue is a complicated matter, being somewhat offset by arousal, alertness and motivation it wou
40、ld be expected that, in addition to being less efficient at night, the driver would be more subject to errors in judgment and even to falling asleep at the wheel. Evidence of this fatigue factor has been given by Solomon 74. He showed that large trucks and buses do not experience a higher accident-i
41、nvolvement rate at night while passenger cars do. It can be argued that professional truck drivers are, as a group, more rested and physiologically prepared for night shifts than the average driver of a passenger car, who has probably worked his normal daytime occupation. 2.4.2.2 Intoxication The ro
42、ad user population changes at night, both in the kind of people using the roads and in the purpose associated with travel, The hours of darkness are those of relaxation and pleasure seeking. This is synonymous with the use of intoxicants, particularly of alcohol. It has been reported 75 that 80 per
43、cent of the drivers fatally injured in single vehicle crashes and who have been drinking, sustained their injuries during the hours of darkness. in contrast only 39 per cent of fatally injured drivers without alcohol involvement sustained their injuries during darkness. Other evidence of the alcohol
44、 factor can be shown when accident rates are plotted by hours of the day. The accident rates tend to nearly double with the onset of darkness and usually double again during the hours shortly after midnight, see Fig 2.2. Therefore alcohol, as well as darkness, could be asignificant causal factor in
45、the elevated night accident situation. One of the effects of alcohol is to impair vision (761 and this could adversely interact with poor visual conditions at night. The major efect of alcohol, however, is the impairment of judgement. This interacts adversely with the fact that at night the proporti
46、on of young inexperienced drivers is higher than daytime. 64. 2.4.2.3 Road user population The younger drivers do more driving at night while older drivers, particularly those 50 or over, do much less driving at night than during the day 74. Younger drivers have a much higher accident rate than thei
47、r elders (there is also an increasing trend for those wer 65, but the increase is not nearly as sharp as for those in the younger age group), The disproportionate number of younger drivers on the road at night is probably reflected in the higher night accident rate. 9 2.4.2.4 Speed and behaviour Mot
48、oring offences, principally excessive speed are more apparent at night. There are many factors which have a great influence on drivers behaviour: less frequent police patrols, lower traffic volume, younger drivers, alcohol, etc. Therefore driving speed and the corresponding severity of accidents inc
49、rease in darkness. 2.4.2.5 Traffic flow At low traffic volumes accident rates increase over the fairly constant value associated with higher volumes 77,78. As was discussed in section 2.3, the volume at night is only about one third or less of that encountered during daylight. Therefore, accident rates might be expected to increase at night because of the generally lower volumes observed. Hartmann and Linde 79, using freeway data, have shown that at night catching up or rear end collisions increased for
