Development and Use of Driving Tests to Evaluate Headlamp Beams
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I--/ Ie ( <.'y+j d' -52 Report No. UM-HSRI-HF-74 -14 DEVELOPMENT AND USE OF DRIVING TESTS TO EVALUATE HEADLAMP BEAMS Rudolf G. Mortimer Paul L. Olson Highway Safety Research Institute The University of Michigan Ann Arbor, Michigan 48205 March 1974 Contract No. UM 7102-C128 Motor Vehicle Manufacturers Association 320 New Center Building Detroit, Michigan 48202 The contents of this report reflect the views of the Highway Safety Research Institute, which is responsible for the facts and the accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the Motor Vehicle Manufacturers Association. HIGHWAY SAFETY RESEARCH INSTITUTE Institute of Sc~enceand Technology Huron Parkway and Baxter Road Ann Arbor, M~ch~gan48105 T,HE UNIVERSITY OF ILIICtllGAN 18 September 1974 Mr. John C, Scowcroft Motor Vehicle Manufacturers Association 320 New Center Building Detroit, Mich. 48202 Dear Mr. Scowcroft: We are sending to you 50 copies of a report entitled "Development and Use of Driving Tests to Evaluate Headlamp Beams," which is a final report describing the field test work carried out in our headlighting project wit'n MW4A under Phases I and 11. These reports should be received by MVMA tomorrow. I hope that this report will be of interest to members of the Lighting Committee, as well as others concerned with matters of vehicle headlighting in the industry. I hope that the report will get fairly wide distribu- tion as I would hope that it could make a contribution in the development of a uniform field testing method. Yours sincerely, Rudolf G. Mortimer, Ph.D. Head, Human Factors ----. - 1_1.- r BlBtlOCRAPHlC DATA 1. 90. 2. 3. Rccip~ent'sAccession No. 5. Kcport Date March 1974 Development and Use of Driving Tests to Evaluate Headlamp Beams 6. 7. Author(s) 8. Prrform~npOrganization Hept. KO. Rudolf G. Mortimer and Paul L, Olson UM-HSRI-HF-74-14 9. I'crforrn~npOrganirat~on Name and Address 10. Project!'Task,.'U'orL Unit No. Highway Safety Research Institute 320015 The University of Michigan 11. Contract /Grant NO. UM7102-C128 Ann Arbor, Michigan 48105 1 1 I 12 Sponsor~n~Organ~zatlon Name and Address 13. Type oi Report & Period I Covered ! Motor Vehicle Manufacturers Association 320 New Center Building Final Report Detroit, Michigan 48202 14. 15. Supplcmcntrry Notes I 16. Abstract. Results of analyses of accldent data to evaluate the contributory role of head- lightrng were inconclusive, Reflectance values of -tarlous objects in the driver's field-of-view welt zieascred. Pllot stud~esktere made to evaluate test targets, and the results were used to describe desirable characteristics of a test target for use in subsequent tests. A series 05 headilghtlng fleld tests were carrled out to develop a rellable field test method, evaluate variables affectinq visibility provided by headlampi, and generate data for use in valldatrng a patheratical model. Drlving tests were also used to evaluate glare effects of various beams to oncomng and preceding drivers. Three types of targets were developed for the work: a simulated overhead sign, a simulated roadslde siqn, and a general purpose target to samulate objects on or near the roadway. The latter target could be placed to the right or left of the test vehicle or in the center of its lam of t:.avel. In addition, its reflectivity could be changed. The following vazlables were investjgated: (1) headlamp bear?, (2) lateral separation between vehicits, (3) longitud~nalseparatioc between vehicles, (4) target type, (5) target reflectivity, (6) tarqet position relative to car path, and (7) target height. ~llof the above varlzbles ;sere found tcj be significantly related to the distance at which the orientstion of the tarqet could be identified. T~~yatep~sitioned to the right of the lane are rtore easily seen than those an the left under glere conditions, and blth low bea~,s. Cther factors heinq equa:, the closer a target is to the ~avencnt,t::a n:c?re easiiy lt is seer.. Petro-reflective tarqets are seen at far areater dis- tances thm palnted tarscts, but very hl;h levels of reflective trllliance say actually impede their legibility by making the target itself a glare source. The test-rctest coefficient of reliability of the field test procedure developed in this prcgram is esti~atedto be 0.97, prcd~lcinga variation OF less than.58 in the visibility dlstances when t!;e sa;..c ju~jectsare retested on the sane nlght. iihen a different crou of subjects, a iif- ferent tec,t rcad, headlarps amed inde?endently cn the two occaslcns, and a stationary glare car In ccu case and a fully dyRaric test ln the other case, were used the differences In the rean vlslb~lityCistances dld not exceed about 15%. Thus, test reliability is considered to be satisfactory. Ccz~lrlso:~sbebeen G.S. low and h14h teacs showed that on two-lane roads visiblllty is greatest if dlrning cccurs from high :o low Deans at about 1500 feet. The U.S. low beam headlamps used In th4:se -,csts proq~idedgreater vislbrlity of a target on the right side of the 1ar.e thar. the Eur~peind4 t,eadiarps that were used. A type of mid be&! provided greater visibility on the rlqht tlhafi the U.S. or European bca-5. Eoad evaluazions of glare fro3 tnc headlarnp bears showed that the European high bean produced relatz9:cly mucn more requests for di:-xng "cn oncomlng drivers than the Y.S. high bean. 3rivcrs also influenced by the nwher of hea6:r.p~ on the onconing vehicle, but not in the case of the following vehicle. Discomfort glare due to beams reflected in rearview mirrors was affected by mirror reflectivity and beam intensity, but not by the presence or absence of road lighting. .. - . - - 17, ~dentifiers/Opan-Ended Term. Beadlamp barn test procedure, glare, headlamp test targets, u.6. ad European beam, night visibility, reuview mirror glare, night driving accidents. - 18. Availability Statement / 19. Securlcy Class (This 121. KO. of Pages I Report) / I':iCLASSIFIED 1 163+ ' 120. Secur~tyClass ('This 122. Price , ~ -0- 1 IiSCLASSIFIED 1 1 FORM NTIS-35 (REV. 3-72) - USCOMM-DC 14052.P72 TABLE OF CONTENTS Abstract Objectives Summary of Findings Foreword and Acknowledgements List of Tables List of Figures Introduction . , . 1 General procedures Used in Field Tests of Visibility Distance. 7 Vehicles. , . 7 Test Targets. 10 Subjects . , 17 Procedure .........................I7 Data Reduction and ~nalysis . 19 Method. 20 Results . 21 Study2 .............................26 Method. 26 Results . 26 Effects of Test Vehicle Speed . 36 Reliability of the Field Test Procedure . 36 36 Study3.e- ... .. ...... ................... Method. 36 41 Results: Type I Targets. , . , . , . Results: Type I1 Targets . 41 Results: Type I11 Targets. 46 Study4 ............................. 46 Method. 46 Results: Type I Targets. 46 Results: Type I1 Targets. 50 Glare Response: Studies 1 - 4 . 50 Method. 50 Results. 56 iii Study 5 ......................... 56 Method ................. 56 Results: Type-I Targets .........62 Results: Type-I1 Targets .........64 Results: Illumination and Glare Ratings . 71 Reliability: Comparison of Study 5 and Studies 1 and 2 . 71 Study6 ..........*..........77 Method ........................ 77 Results ........................ 78 Study7 e*78 Method ........................ 78 Results ....................... 81 Discussion ................... 81 Lampsystems ..................... 81 Lateral Separation .................. 83 Target Location .................... 85 Target Reflectivity .................. 85 General Conclusions .................... 86 References ........................ 89 Appendices ........................ 92 Appendix A: Dimensional Drawings of the Three Types of Targets Used in the Tests ............. 93 Appendix B: Instructions to Test the Subjects .... 98 Appendix C: Preliminary Evaluation of Targets for Use in Headlamp Beam Field Tests ...........108 Appendix D: Reflectance of Some Objects in a Driver's Visual Environment .............122 Appendix E: Comparison of Day and Night Crashes to Discern the Contribution of Vehicle Headlighting . 130 Addendum: Tables E.5.E.8 ...............141 OBJECTIVES The objectives of these studies were: 1. Conduct an analysis of accident data to try to discern the role of vehicle headlighting in crashes. 2. Devise a set of targets for use in field tests of head- lamp performance in terms of the drivers' visibility aistance, and measure reflectance values of objects in the driver's field- of- view. 3. Develop a field test data collection and analysis method. 4. Conduct evaluations using the method to determine its reliability, and to provide basic data of the effects upon visi- bility distance of variables such as beam pattern, target loca- tion, target reflectance, etc., for subsequent use in validating an analytical model. 5. Conduct road tests to evaluate headlamp beams in terms of glare responses of oncoming drivers and those in a preceding vehicle due to rearview mirrors. SUMMARY OF FINDINGS 1. An analysis of accident data was made by comparing the relative frequency of classes of accidents in the day and night, without finding any evidence to show that headlighting was an involved element. This does not mean that headlighting is not involved in night crashes, however, nor that improved lighting would not help to reduce such crashes. 2. Photometric measurements of the reflectance of pavements, road delineation lines, and other objects in the drivers' field- of-view show most of these to have reflectances of 0.10-0.30. 3, A number of preliminary tests were made of various visi- bility targets by which the characteristics of a suitable target were evolved. 4. A general purpose (Type I) target was developed requir- ing recognition of the orientation of the target face. The target can be placed on the right or left of the lane or in the center of the lane in the path of the vehicle. Two other targets, using reflectorized materials, were also used. 5, A dynamic field test procedure was developed and used to measure the visibility distance of the test targets in a variety of test treatments.