1、_ SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising there
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4、SA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE values your input. To provide feedbackon this Technical Report, please visit http:/www.sae.org/technical/standards/J2738_201104 SURFACE VEHICLE INFORMATION REPORT J2738 APR2011 Issued 2005-10 Reaffirmed 2011-0
5、4 Superseding J2738 OCT2005 Improved Roadway Illumination: Information Resource RATIONALE SAE J2738 has been reaffirmed to comply with the SAE 5-Year Review policy. TABLE OF CONTENTS 1. Scope . 2 2. References. 3 3. Introduction 3 3.1 Responses to Lighting 3 3.2 Characteristics of Lighting 3 3.3 Res
6、earch Methods. 4 4. Intensity and Illuminance 4 4.1 Analytical Methods. 4 4.2 Laboratory and Field Methods . 5 5. Aim and Shape of the Beam Pattern . 5 5.1 Analytical Methods. 5 5.2 Laboratory and Field Methods . 5 6. Location and Mounting Height . 5 6.1 Analytical Methods. 5 6.2 Laboratory and Fiel
7、d Methods . 6 7. Dirt and Water 6 7.1 Analytical Methods. 6 7.2 Laboratory and Field Methods . 6 8. Spectral Power Distribution 6 8.1 Analytical Methods. 6 8.2 Laboratory and Field Methods . 7 9. System Life and Reliability. 7 9.1 Analytical Methods. 7 9.2 Laboratory and Field Methods . 7 SAE J2738
8、Reaffirmed APR2011 Page 2 of 34 10. Discussion 8 11. References. 8 11.1 Importance of Lighting 8 11.1.1 Lighting, Visibility and Crashes 8 11.1.2 Crash Statistics 9 11.2 Characteristics of Lighting and Impact on Vision. 9 11.2.1 On-Axis and Off-Axis Vision. 9 11.2.2 Glare. 10 11.2.3 Spectrum 16 11.2
9、.4 Light Output, Intensity and Illumination 17 11.2.5 Driver Age Effects 18 11.3 Technical Aspects of Forward Lighting 19 11.3.1 Forward Lighting Task and Design Goals 19 11.3.2 Headlamp Beam Patterns 20 11.3.3 Headlamp Mounting Height . 20 11.3.4 Headlamp Leveling 20 11.3.5 Headlamp Cleaning 21 11.
10、3.6 AFS Headlamps . 21 11.3.7 Lighting on Trucks and Buses 30 11.3.8 Lighting on Motorcycles . 31 11.4 Light Source Technology . 31 11.4.1 Halogen Sources 31 11.4.2 Xenon Gas Discharge (or High-Intensity Discharge (HID) Sources. 31 11.4.3 LED Light Sources . 32 11.4.4 Distributive Lighting, Fiber Op
11、tics and Light Pipes 32 11.5 Roadway Lighting System . 33 11.5.1 System Interaction and Optimization . 33 11.6 Regional Differences 33 11.6.1 U.S. Beam Patterns in Comparison to European and Japanese Patterns 34 1. Scope Headlamps should illuminate the traffic scene ahead of the vehicle in such a wa
12、y that the driver can operate the vehicle safely and in a relaxed manner. At the same time, negative effects on drivers of other vehicles, pedestrians and other people should be minimized. Various technical parameters such as beam pattern, mounting height, headlamp aiming, and source spectrum can be
13、 tuned to find the necessary compromise. The physiology of the vision system under specific night time conditions strongly influences these factors and how headlamps can be best optimized for visibility and comfort. The SAE Improved Roadway Illumination task force collected and reviewed relevant res
14、earch on these topics. This document is a comprehensive summary of this information. The goal is to enable lighting experts, advocacy groups, and non-experts (journalists, consumer organizations, car drivers) to better understand the benefits and tradeoffs of improved roadway lighting with modern he
15、adlamp technology. It should be noted that all studies can not be included in this report, but the intent of this document is to provide the reader with a representative sample of the existing research as a starting point. Further, this document can be updated in the future to reflect new research f
16、indings. SAE J2738 Reaffirmed APR2011 Page 3 of 34 2. References See Section 11 for references. 3. Introduction This report outlines a literature review to further our understanding of vehicle forward lighting and how it can be best optimized for visibility and comfort. 3.1 Responses to Lighting For
17、ward lighting on vehicles serves a number of objectives that are to be met simultaneously for the vehicle driver and other roadway users. These include: providing adequate forward visibility on and along the roadway providing peripheral visibility so that potential hazards not yet along the roadway
18、can be detected maximizing driver comfort while minimizing discomfort to other drivers providing attractive appearance These responses serve as the end objectives of lighting from the users point of view. In order to meet these objectives, lighting systems must be developed with the appropriate char
19、acteristics. 3.2 Characteristics of Lighting It is not enough to say simply that a forward lighting system should “provide adequate forward visibility“ or “maximize comfort.“ In order to meet these objectives, specific aspects of lighting can be manipulated. These aspects form the palette of the lig
20、hting system designer, and include: intensity or illuminance aim, shape, uniformity of the beam pattern change of beam pattern (intelligence) location and mounting height of the light sources effects of dirt and water spectral power distribution color system life and reliability One of the objective
21、s of the present report is to summarize existing information about these characteristics of lighting. SAE J2738 Reaffirmed APR2011 Page 4 of 34 3.3 Research Methods The information summarized in this report is based on a combination of techniques and methods, including: analytical methods based on c
22、alculation using existing models of expected performance short-term laboratory and field study methods, directly measuring lighting or testing human responses to lighting long-term laboratory and field study methods, using simulation or observational techniques to understand how responses might chan
23、ge under long-term exposure to different lighting conditions In the present report, each of the characteristics or aspects of forward lighting are discussed with respect to the different methods of understanding them. Brief summaries of important investigations of these aspects of lighting are also
24、provided. 4. Intensity and Illuminance 4.1 Analytical Methods One of the most important factors related to the success of forward lighting systems is the intensity (or illuminance) the system provides. A number of quantitative models for predicting visual performance as a function of light level exi
25、st. One of the most important is the relative visual performance (RVP) model (Rea and Ouellette, 1991), which provides a prediction for the speed and accuracy of visual processing as a function of adaptation level, target size and contrast, and observer age. Another model used widely in the specific
26、ation of roadway lighting in North America is the small target visibility (STV) model. Interestingly, this model does not incorporate the effects of headlamps, but it was found recently (Keck, 2001) that while the prediction for visibility provided by STV is not correlated with vehicle crashes, a mo
27、dification of the model to incorporate headlamp illumination did result in a small but significant correlation with vehicle crashes, underscoring the importance of considering all roadway visibility elements. In terms of peripheral visibility, few data are available upon which to make predictions. O
28、ne recently developed model, still in preliminary form, uses the results of a series of similar investigations of forward visibility under headlamps and data on the detection of small targets located throughout the peripheral field of view. Combining results in this way provided a robust data set th
29、at provided a predictive model for peripheral visibility under different types of headlamp beams (Bullough, 2002). Of course, not only forward visibility, but the potential for disability and discomfort glare are impacted by the intensity of a forward lighting system. Formulae for the prediction of
30、disability glare (Fry, 1954) have been found to quite accurately predict the reduction in visibility that is caused by oncoming headlamps in the field of view. Similar formulae exist to predict the extent of discomfort felt under oncoming headlamp illumination (Schmidt-Clausen and Bindels, 1974), si
31、nce discomfort and reduced visibility do not necessarily go hand in hand. SAE J2738 Reaffirmed APR2011 Page 5 of 34 4.2 Laboratory and Field Methods The study of forward visibility using field methods is common and generally has used techniques like the measurement of reaction times and missed targe
32、ts (Van Derlofske et al., 2001, 2002) and target visibility distance in the field of view (Hamm and Steinhard, 1999). These results generally are in agreement with model predictions. One technique for assessing long-term performance and impacts of forward lighting involves the use of surveys and que
33、stionnaires to gauge drivers acceptance and opinions about forward lighting. A recent survey of snowplow operators to ask what types of forward lighting were most suitable when driving in snow were fond to exhibit excellent agreement with field studies comparing different forward lighting configurat
34、ions (Eklund et al., 1997). 5. Aim and Shape of the Beam Pattern 5.1 Analytical Methods One approach to understanding the impact of forward lighting beam patterns and aim is to quantify the types of forward lighting beam patterns used in a given jurisdiction. Market-weighted beam patterns providing
35、average intensity values for a range of angles (i.e. Schoettle et al., 2001) provide useful analytical tools for estimating typical forward lighting configurations on the road. These data could be used in turn with models providing predictions of visibility and other responses. For example, Bullough
36、 and Rea (1997) developed a model to predict the impact of beam shape and aiming on subjective impressions of visibility and comfort while driving in poor weather. Such models and tools will be useful in the study of adaptive beam patterns that can adjust in responses to changes in the ambient envir
37、onment. 5.2 Laboratory and Field Methods The basis for many models to assess aim and beam pattern effectiveness will often need to be field studies where these patterns can be replicated most accurately. Comparisons of different beam pattern types for the distance at which targets can be detected is
38、 one such approach (Flannagan et al., 1995). Other responses to beam patterns might also be important, such as comfort while driving or even aesthetic appearance while performing a test drive. Studies of subjective impressions of headlamp beam uniformity have shown that this characteristic of lighti
39、ng is often seen as important in providing visibility and maintaining visual comfort while driving (Schumann et al., 1997). 6. Location and Mounting Height 6.1 Analytical Methods The mounting location and height of forward lighting sources can have a significant impact on driver visibility and comfo
40、rt. Analytical tools for the assessment of the effects of these parameters include the model, described above, by Bullough and Rea (1997) to predict preferences of forward lighting as a function of mounting location, which in turn impacts the distance of the source from the line of sight. This facto
41、r is found to determine the intensity of back-reflected light in snow and fog conditions. SAE J2738 Reaffirmed APR2011 Page 6 of 34 A simulation-based approach to predicting the effectiveness of forward lighting configurations was developed and refined by Mortimer (1974). Based on actual photometric
42、 measurements and responses to targets in field studies, a scenario-based simulation tool was developed that could then be used to compare various lighting configurations without conducting additional field studies. 6.2 Laboratory and Field Methods Measurements of the range of conditions that can be
43、 experienced in the field is a useful approach to characterizing lighting. Field measurements of headlamp height and separation (Sivak et al., 2001) can provide data that will in turn support more refined laboratory and analytical approaches to studying lighting. 7. Dirt and Water 7.1 Analytical Met
44、hods Few studies, if any, have provided tools for calculating or predicting the impact of dirt and water on forward lighting system performance. 7.2 Laboratory and Field Study Methods All lighting and visibility systems along the roadway will undergo inevitable reductions in visibility caused by dir
45、t or by water introduced by rain. These phenomena simultaneously reduce the illuminances produced by lighting systems in the points of their maximum intensity, reducing forward visibility, and increase illuminances along the points of their minimum intensity, potentially increasing glare. Studies of
46、 other visibility elements (e.g., signs, see Colomb and Michaut, 1986) can perhaps be useful in better understanding the effects of dirt and water on headlamps. Of interest, a number of jurisdictions already require the use of headlamp cleaning devices in conjunction with certain headlamp technologi
47、es such as high intensity discharge headlamps. Thus the problem might be one of implementation countermeasures rather than changing lighting to adapt to conditions of dirt or water. 8. Spectral Power Distribution 8.1 Analytical Methods For forward visibility in terms of color rendering, the commonly
48、 accepted industry metric for predicting the ability of a light source to render colors well is the color rendering index (CRI) (Rea, 2000). In effect, this metric compares a light sources ability to render colors similarly to a reference source, either an incandescent lamp (for a yellowish-white so
49、urce) or daylight (for a bluish-white source), not necessarily ones ability to accurately identify colors under that source. The gamut area metric (Boyce, 2003) appears to better predict the ability of a light source to result in accurate color identification. SAE J2738 Reaffirmed APR2011 Page 7 of 34 In terms of forward visibility, spectrum can play a role at mesopic light levels, where both cones and rods pr
