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REVIEWING THE EVIDENCE |
The authors are with the Insurance Institute for Highway Safety, Arlington, Va.
Correspondence: Requests for reprints should be sent to Richard A. Retting, MS, Insurance Institute for Highway Safety, 1005 N Glebe Rd, Arlington, VA 22201 (e-mail: rretting{at}iihs.org).
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONTRAFFIC ENGINEERING...DISCUSSIONReferences |
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We provide a brief critical review and assessment of engineering modifications to the built environment that can reduce the risk of pedestrian injuries.
In our review, we used the Transportation Research Information Services database to conduct a search for studies on engineering countermeasures documented in the scientific literature. We classified countermeasures into 3 categories—speed control, separation of pedestrians from vehicles, and measures that increase the visibility and conspicuity of pedestrians. We determined the measures and settings with the greatest potential for crash prevention.
Our review, which emphasized inclusion of studies with adequate methodological designs, showed that modification of the built environment can substantially reduce the risk of pedestrian–vehicle crashes.
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONTRAFFIC ENGINEERING...DISCUSSIONReferences |
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In terms of constructing a framework for prevention of pedestrian injuries, primary approaches include modification of the built environment, enforcement of traffic safety laws, motor vehicle design changes, and pedestrian education. Modification of car fronts and other vehicle features to reduce the severity of injuries to pedestrians is a focus in Europe, where approximately 20% of all fatalities among road users involve pedestrians and cyclists8; however, this approach has not been a priority in the United States despite research showing potential benefits.9
Pedestrian education is a popular approach, but with the exception of children, there is a lack of evidence regarding the effectiveness of safety education.10–12 Modification of the built environment is a widely used approach that can be highly effective. In this article, we provide a brief review of engineering modifications to the built environment that can reduce the risk and severity of pedestrian injuries.
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TRAFFIC ENGINEERING COUNTERMEASURES |
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TOPABSTRACTINTRODUCTIONTRAFFIC ENGINEERING...DISCUSSIONReferences |
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Separation countermeasures reduce the exposure of pedestrians to potential harm both on the roadside and when they are crossing streets. Because in many pedestrian crashes the driver reportedly does not see the pedestrian before the accident, measures are needed to increase the visibility and conspicuity of pedestrians. Higher vehicle speeds are strongly associated with a greater likelihood of crashes involving pedestrians as well as more serious pedestrian injuries.13–15
We undertook a thorough review of traffic engineering countermeasures documented in the scientific literature as effective in reducing the risk of crashes involving pedestrians. The primary search engine used was the National Academy of Sciences’ Transportation Research Information Services (TRIS) database. TRIS is the world’s largest and most comprehensive bibliographic resource on transportation information. Keywords were pedestrians along with injuries, safety, reduction, countermeasures, and crosswalks. In terms of study types, we included before–after, case–control, and cross-sectional studies of the effects of speed reduction, separation, or visibility enhancement measures on the occurrence of pedestrian–vehicle collisions or conflicts.
Many studies of traffic engineering measures are limited by methodological flaws such as failure to account for regression to the mean associated with treatment of high-crash locations and reliance on simple before–after measurements without suitable controls. To the extent possible, we included in our review studies based on adequate scientific criteria, such as use of comparison sites to control for confounding factors. In the case of several promising countermeasures, only limited evaluations with somewhat less reliable methodologies were available.
A common weakness in many crash-based before-and-after evaluations of traffic engineering countermeasures is failure to account for regression to the mean, which can result in overestimation of the effects of an intervention when treatment sites are selected because they have involved high numbers of crashes. Selection of comparison sites with similar characteristics can partially, but not fully, address regression to the mean. We included in our review several studies with methodological weaknesses; in these cases, we make note of their limitations.
Some researchers conducting observational road safety studies evaluate pedestrian–motor vehicle conflicts in lieu of crash data to evaluate roadway countermeasures, in part because crashes are rare events and because conflict studies provide information about potential crash causes. Conflicts generally are defined as "near-miss" situations in which a vehicle had to abruptly brake or swerve to avoid striking a pedestrian or a pedestrian had to take sudden evasive action to avoid being struck. The validity of using conflicts to estimate crashes was examined by Hauer and Garder16 and Garder.17 Hauer and Garder formulated and tested statistical methods to measure the validity of traffic conflicts on the basis of empirical evidence. According to Garder, it can be shown that a 1-day conflict count provides a more accurate estimate of the expected number of crashes than a 1-year crash history if the expected number of crashes is less than 5 per year. In conflict studies and other short-term before–after evaluations of road user behavior, regression to the mean associated with treatment of high-crash locations is not a factor.
Managing Vehicle Speeds
Principal engineering measures designed to reduce vehicle speeds are summarized in Table 1
. In residential settings with large numbers of children, speed management appears to offer the greatest potential for injury prevention. Pedestrian crashes involving a child most often result from the child’s error. Slower speeds give motorists more time to react and can lessen injuries when crashes do occur. Slower speeds are desirable in areas with pedestrians because many young children fail to stop before proceeding from the curb onto the road24; Kraus et al.25 reported that 69% of child pedestrian injuries occur midblock, when children dart into the street. Young children have difficulty judging vehicle distance and velocity26 and lack the relevant cognitive skills required to make valid and consistent crossing judgments.27
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Other speed management measures include traffic calming and multiway stop sign control. Traffic calming techniques include lane narrowing, adjustments in roadway curvature, pedestrian refuge islands, and speed humps. Although traffic calming measures clearly are effective in reducing traffic speeds (e.g., see Smith and Appleyard28), effects on pedestrian–vehicle crashes are less certain. One study of "extensive" area-wide traffic calming measures, involving a before–after design without controls, reported that pedestrian–vehicle crashes decreased 25% after implementation of these measures.21 However, a recent review of 13 controlled before–after studies of area-wide traffic calming reported no overall effect on pedestrian–vehicle crashes.22 An investigation focusing on multiway stop sign control, which produces low vehicle speeds near intersections relative to traffic signal control or conventional 2-way stop signs, showed that pedestrian collisions decreased by 25% when multiway stop signs were installed in place of traffic signals at lowtraffic-volume urban intersections.23
Separating Pedestrians and Vehicles
Engineering measures intended to separate pedestrians and vehicles by time are summarized in Table 2. These interventions have generally been evaluated in terms of their effects on road user behavior and pedestrian–vehicle conflicts rather than crashes, and their use is somewhat site dependent. One study reported that installation of traffic signals substantially reduced conflicts occurring at high-speed intersections where previously no signals were present and pedestrians had difficulty crossing.30 At intersections with traffic signals, exclusive traffic signal phasings—which stop all vehicle traffic for part or all of the pedestrian crossing signal—have been shown to significantly reduce conflicts.30,31 A comparative analysis of intersections with and without exclusive pedestrian signal phasings reported that the risk of pedestrian–vehicle crashes at intersections with exclusive timing was approximately half that at intersections with standard pedestrian signals.29
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Also, traffic signs and pavement markings that encourage pedestrians to look for potential conflicts have been shown to be effective at intersections with traffic signals.33 In addition, 2 studies showed that vehicle speeds and conflicts at uncontrolled crossings were reduced by in-pavement flashing lights that were automatically activated by the presence of pedestrians and were intended to prompt drivers to yield to pedestrians.35,36
Engineering measures designed to separate pedestrians and vehicles by space are summarized in Table 3. Several highly effective interventions were identified. Overpasses and underpasses can substantially reduce conflicts and associated pedestrian crashes.38 However, the high cost of such facilities requires that they be installed on a very limited basis—for example, at very wide crossings and at those with high traffic speeds. Safety effects may be limited in instances in which pedestrians are reluctant to use such facilities because of security concerns or inconvenient access points. Sidewalks can reduce the risk of pedestrian crashes in residential areas.42
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Barriers and fences, which are designed to channel pedestrians to safe crossing areas and prevent them from running into traffic, have been found to reduce midblock crossings39 and substantially decrease crash rates.41 An inexpensive intervention at signal-controlled intersections involves repositioning of stop lines further back from crosswalks. This results in drivers stopping further back from crosswalks, thus increasing the separation between pedestrians and vehicles.39,40
Increasing Pedestrian Visibility
Engineering measures designed to increase the visibility and conspicuity of pedestrians are summarized in Table 4. Increased intensity of roadway lighting can increase pedestrians’ visibility at night, when more than half of all fatal pedestrian crashes occur.1 Increased intensity of roadway lighting at pedestrian crossings has been associated with significant reductions in nighttime pedestrian crashes.44,45
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In addition, relocating bus stops from the near side to the far side of intersections can increase the visibility and conspicuity of pedestrians by decreasing the number of pedestrians who enter the roadway in front of a stopped bus. It has been shown that bus stop relocation significantly decreases the percentage of pedestrians who enter the roadway in front of a stopped bus at signalcontrolled intersections.39 Crosswalk pavement markings are widely used with the intent of reducing pedestrian crashes, but research indicates that they are largely ineffective and, in some settings, may be harmful.43,46
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONTRAFFIC ENGINEERING...DISCUSSIONReferences |
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Highly effective countermeasures include single-lane roundabouts, sidewalks, exclusive pedestrian signal phasing, pedestrian refuge islands, and increased intensity of roadway lighting. Other countermeasures, including advance stop lines, in-pavement flashing lights, and automatic pedestrian detection at walk signals, are promising but have been evaluated on a more limited basis. In the case of many traffic engineering measures, more definitive research is needed to establish their effects on pedestrian–vehicle crash risks.
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Acknowledgments |
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We would like to acknowledge Dr Allan F. Williams for reviewing and contributing to this article.
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Footnotes |
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Accepted for publication April 8, 2003.
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References |
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TOPABSTRACTINTRODUCTIONTRAFFIC ENGINEERING...DISCUSSIONReferences |
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2. National Electronic Injury Surveillance System—All Injury Program Operated by the US Consumer Product Safety Commission. Atlanta, Ga: National Center for Injury Prevention and Control; 2002.
3. Insurance Institute for Highway Safety. Fatality facts 2001: pedestrians. Available at: http://www.hwysafety.org/safety_facts/fatality_facts/pedestrians.pdf. Accessed January 31, 2003.
4. Knoblauch R, Nitzburg M, Dewar R, Templer J, Pietrucha M. Older Pedestrian Characteristics for Use in Highway Design. Washington, DC: US Dept of Transportation; 1995. DOT publication FHWA-RD-93-177.
5. McCarroll JR, Braunstein PW, Cooper W, et al. Fatal pedestrian automotive accidents. JAMA.1962;180:127–133.
6. Curtin D, Syner J, Vegega M. Alcohol involvement in pedestrian fatalities—United States, 1982–1992. MMWR Morb Mortal Wkly Rep.1993;42:716–719.[Medline]
7. Vestrup JA, Reid JDS. A profile of urban adult pedestrian trauma. J Trauma. 1989;29:741–745.[Web of Science][Medline]
8. Hobbs A. Safer Car Fronts for Pedestrians and Cyclists. Brussels, Belgium: European Transport Safety Council; 2001.
9. Vehicle Designs Affect the Harm That’s Inflicted on Pedestrians. Arlington, Va: Insurance Institute for Highway Safety; 1999:4–5. Status report 34/3.
10. O’Neill B, Mohan D, Breen J, et al. Commentary on the World Bank’s Global Road Safety Partnership. Traffic Inj Prev.2002;3:190–194.
11. Duperrex O, Bunn F, Roberts I. Safety education of pedestrians for injury prevention: a systematic review of randomized controlled trials. BMJ.2002;324:1129–1133.
12. Weiner EL. The elderly pedestrian: response to an enforcement campaign. Traffic Safety Res Rev.1968;11:100–110.
13. Pitt R, Guyer B, Hsieh C, Malek M. The severity of pedestrian injuries in children: an analysis of the Pedestrian Injury Causation Study. Accid Anal Prev.1990;22:549–559.[Web of Science][Medline]
14. Pasanen E, Salmivaara H. Driving speeds and pedestrian safety in the city of Helsinki. Traffic Eng Control. June 1993:308–310.
15. Leaf WA, Preusser DF. Literature Review on Vehicle Speeds and Pedestrian Injuries. Washington, DC: US Dept of Transportation; 1999. DOT publication HS 809 021.
16. Hauer E, Garder P. Research into the validity of the traffic conflicts technique. Accid Anal Prev.1986;18:471–481.[Web of Science][Medline]
17. Garder P. Theory for strong validation, application of Swedish results. In: Proceedings From Evaluation 85: International Meeting on the Evaluation of Local Traffic Safety Measures. Paris, France: Organisation National de Securite Routiere; 1985.
18. Brilon W, Stuwe B, Drews O. Sicherheit und Leistungsfahigkeit von Kreisverkehrsplatzen. Bochum, Germany: Lehrstuhl fur Verkehrswesen, Ruhr-Universitat Bochum; 1993. Cited by: Elvik R. Effects on road safety of converting intersections to roundabouts: a review of evidence from non-US studies. Transportation Res Rec. In press.
19. Schoon C, van Minnen J. The safety of roundabouts in the Netherlands. Traffic Eng Control. March 1994:142–148.
20. Brude U, Larsson J. What roundabout design provides the highest possible safety? Nordic Road Transport Res.2000;12:17–21.
21. Brilon W, Blanke H. Extensive traffic calming: results of the accident analyses in six model towns. In: Proceedings of the 63rd Annual Meeting of the Institute of Transportation Engineers. Washington, DC: Institute of Transportation Engineers; 1993:119–123.
22. Bunn F, Collier T, Frost C, Ker K, Roberts I, Wentz R. Area-Wide Traffic Calming for Preventing Traffic Related Injuries. Oxford, England: Update Software; 2003.
23. Persaud B, Hauer E, Retting RA, Vallurupalli R, Mucsi K. Crash reductions related to traffic signal removal in Philadelphia. Accid Anal Prev.1997;29:803–810.[Web of Science][Medline]
24. Zeedyk MS, Wallace L, Spray L. Stop, look, listen and think? What young children really do when crossing the road. Accid Anal Prev.2002;34:43–50.[Web of Science][Medline]
25. Kraus JF, Hooten EG, Brown KA, Peek-Asa C, Heye C, McArthur D. Child pedestrian and bicyclist injuries: results of community surveillance and a case-study control. Inj Prev.1996;2:212–218.
26. Phinney J, Colker L, Cosgrove M. Literature Review on the Preschool Pedestrian. Washington, DC: US Dept of Transportation; 1985. DOT publication HS-806-679.
27. Embry DD, Malfetti JM. Stay Out of the Street! Reducing the Risk of Pedestrian Accidents to Preschool Children Through Parent Training and Symbolic Modeling. Falls Church, Va: AAA Foundation for Traffic Safety; 1981. Safe Playing Project report 2.
28. Smith DT Jr, Appleyard D. Improving the Residential Street Environment—Final Report. Washington, DC; US Dept of Transportation; 1981. DOT publication FHWA-RD-81/031.
29. Zegeer CV, Opiela KS, Cynecki MJ. Effect of pedestrian signals and signal timing on pedestrian accidents. Transportation Res Rec.1982;847:62–72.
30. Garder P. Pedestrian safety at traffic signals: a study carried out with the help of a traffic conflicts technique. Accid Anal Prev.1989;21:435–444.[Web of Science][Medline]
31. Van Houten R, Retting RA, Farmer C, Van Houten J. Field evaluation of a leading pedestrian interval signal phase at three urban intersections. Transportation Res Rec.2000;1734:86–92.
32. Retting RA, Chapline JF, Williams AF. Changes in crash risk following re-timing of traffic signal change intervals. Accid Anal Prev.2002;34:215–220.[Web of Science][Medline]
33. Retting RA, Van Houten R, Malenfant L, Van Houten J, Farmer CM. Special signs and pavement markings improve pedestrian safety. ITE J.1996;66:28–35.
34. Hughes R, Huang H, Zegeer C, Cynecki M. Automated detection of pedestrians in conjunction with standard pedestrian push buttons at signalized intersections. Transportation Res Rec.2000;1705:32–39.
35. Hakkert AS, Gitelman V, Ben-Shabat E. An evaluation of crosswalk warning systems. In: Proceedings of the 80th Annual Meeting of the Transportation Research Board [CD-ROM]. Washington, DC: Transportation Research Board; 2001.
36. Prevedouros PD. Evaluation of in-pavement flashing lights on a six-lane arterial pedestrian crossing. In: Proceedings of the 71st Annual Meeting of the Institute of Transportation Engineers [CD-ROM]. Washington, DC: Institute of Transportation Engineers; 2001.
37. Coffin A, Morrall J. Walking speeds of elderly pedestrians at crosswalks. Transportation Res Rec.1995;1487:63–67.
38. Accident Prevention Effects of Road Safety Devices. Tokyo, Japan: Japan Road Association; 1969.
39. Berger WG. Urban Pedestrian Accident Countermeasures Experimental Evaluation: Volume 1—Behavioral Studies. Washington, DC: US Dept of Transportation; 1975. DOT publication HS-801-346.
40. Retting RA, Van Houten R. Safety benefits of advance stop lines at signalized intersections: results of a field evaluation. ITE J.2000;70:47–54.
41. Stewart D. Pedestrian guard rails and accidents. Traffic Eng Control.1988;29:450–455.
42. Knoblauch RL, Tustin BH, Smith SA, Pietrucha MT. Investigation of Exposure-Based Pedestrian Accident Areas: Crosswalks, Sidewalks, Local Streets, and Major Arterials. Washington, DC: US Dept of Transportation; 1987. DOT publication FHWA-RD-87-038.
43. Zegeer CV, Stewart JR, Huang H, Lagerwey P. Safety effects of marked versus unmarked crosswalks at uncontrolled locations. Transportation Res Rec.2001;1723:56–68.
44. Pegrum BV. The application of certain traffic management techniques and their effect on road safety. In: Proceedings of the National Road Safety Symposium. Perth, Western Australia: Dept of Shipping and Transport; 1972:277–286.
45. Polus A, Katz A. An analysis of nighttime pedestrian accidents at specially illuminated crosswalks. Accid Anal Prev.1978;10:223–228.
46. Koepsell T, McCloskey L, Wolf M, et al. Crosswalk markings and the risk of pedestrian-motor vehicle collisions in older pedestrians. JAMA.2002;288:2136–2143.
47. Agran PF, Winn DG, Anderson CL, Tran C, Del Valle CP. The role of physical and traffic environment in child pedestrian injuries. Pediatrics.1996;98:1096–1103.
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