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Suggested Citation:"Summary ." National Academies of Sciences, Engineering, and Medicine. 2017. Development of Crash Modification Factors for Uncontrolled Pedestrian Crossing Treatments. Washington, DC: The National Academies Press. doi: 10.17226/24627.
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Suggested Citation:"Summary ." National Academies of Sciences, Engineering, and Medicine. 2017. Development of Crash Modification Factors for Uncontrolled Pedestrian Crossing Treatments. Washington, DC: The National Academies Press. doi: 10.17226/24627.
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Page 2
Page 3
Suggested Citation:"Summary ." National Academies of Sciences, Engineering, and Medicine. 2017. Development of Crash Modification Factors for Uncontrolled Pedestrian Crossing Treatments. Washington, DC: The National Academies Press. doi: 10.17226/24627.
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Page 3

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1 S u m m a r y There continues to be a problem in the United States related to safety for pedestrians who attempt to cross streets, particularly on high-speed, high-volume, multi-lane roads. Furthermore, there is a need to better understand the safety effects of some of the more promising treatments on pedestrian crashes. The purpose of this study was to develop crash modification factors (CMFs) for selected types of pedestrian treatments at unsignalized pedestrian crossings. After considering numerous treatment options related to geometric design and traffic control devices, the four unique treatment types selected for evaluation in this study included rectangular rapid flashing beacons (RRFBs), pedestrian hybrid beacons (PHBs), pedestrian refuge islands, and advanced YIELD or STOP markings and signs. A total of approximately 1,000 treatment and comparison sites were selected from 14 different cities throughout the United States. Most of the study sites selected were intersections on urban, multi-lane streets, since there is a high risk for pedestrian crashes at these sites and countermeasures are typically most needed. Based on detailed information obtained from each city regarding available treatments of interest for this study, U.S. geographic distribu- tion of cities, and other factors, the 14 cities selected for data collection for this study were Alexandria and Arlington, Virginia; Cambridge, Massachusetts; Chicago, Illinois; New York, New York; Miami and St. Petersburg, Florida; Tucson, Scottsdale, and Phoenix, Arizona; Portland and Eugene, Oregon; Charlotte, North Carolina; and Milwaukee, Wisconsin. For each study site, relevant data were collected on the treatment characteristics, pedes- trian and motor vehicle volumes, geometric features, roadway variables, and pedestrian crashes and other crash types that occurred at each site. Efforts were also made to determine the changes in signs, markings, and geometry that occurred at the treatment and compari- son sites over the analysis period so such changes could be accounted for in the analysis and modeling phase of the study. Data analysis involved the development of cross-sectional models and before/after Empiri- cal Bayesian analysis techniques to determine the crash effects (i.e., CMFs) of each treatment type. The data analysis revealed that all four of the treatment types were associated with reductions in pedestrian crash risk, compared to the comparison (untreated) sites. The CMFs for pedestrian crashes are the following: PHBs (CMF of 0.453) and PHBs with advanced YIELD or STOP signs and markings (CMF of 0.432) were associated with the greatest ben- efit to pedestrian crash risk, followed by RRFBs (CMF of 0.526), pedestrian refuge islands (CMF of 0.685), and advanced YIELD or STOP signs and markings (0.75). The CMFs for PHBs and PHBs with advanced YIELD or STOP markings and signs were statistically differ- ent from 1.0 at the 0.05 significance level. CMFs for some other crash types (e.g., rear-end, sideswipe, and total crashes) were also found for some of the four pedestrian treatments. The CMF for the RRFB was based on a very limited sample (i.e., 50 treatment sites) and hence should be used with caution. Development of Crash Modification Factors for Uncontrolled Pedestrian Crossing Treatments

2 Development of Crash modification Factors for uncontrolled Pedestrian Crossing Treatments A summary of recommended CMFs developed in this study is given in Table S-1. As a general caution, in the application of the CMFs, users should consider the summary statis- tics in Chapter 4 of this report to see how closely the site under consideration for one of these treatments resembles the sites used to develop the CMF. Specifically, the CMFs developed in this study are most appropriate for urban, multi-lane intersection and midblock locations in urban (and suburban) areas. Attempts were also made to develop reliable crash modification functions (CMFunctions), that is, equations that allow for determining differences in crash effects as a function of vehicle or pedestrian volumes, number of travel lanes, vehicle speeds, and/or other roadway features. The development of such CMFunctions was considered desirable by local and state agency officials for use in making decisions on which sites would be most or least appropriate for installing various pedestrian treatment types. Unfortunately, these CMFunctions did not provide useful results. Future research could not only develop more robust CMFs, but also investigate whether these treatments are more or less effective under different conditions. To these ends, and given the challenges of acquiring large samples of pedestrian crash and exposure data, it is recommended that the data from this project remain accessible for future research that could also include development of enhanced safety performance functions for pedestrians. As a result of the CMFs developed in this study, there are several potential resources in which research results from NCHRP Project 17-56 could be integrated to facilitate imple- mentation of the findings in practice. These include the following: • AASHTO’s Highway Safety Manual (HSM) (67); • AASHTO’s Guide for the Planning, Design, and Operation of Pedestrian Facilities (69); • FHWA Pedestrian Safety Guide and Countermeasure Selection System (PEDSAFE) website; Table S-1. Recommended CMFs. Treatment Crash Type Recommended CMF Study Basis Estimate Standard Error Refuge Island Pedestrian 0.685 0.183 Median from two studies Total 0.742 0.071 Cross-section All Injury 0.714 0.082 Cross-section Rear-End/Sideswipe Total 0.741 0.093 Cross-section Rear-End/Sideswipe Injury 0.722 0.106 Cross-section Advanced YIELD or STOP Markings and Signs Pedestrian 0.750 0.230 Median from two studies Total 0.886 0.065 Before-after Rear-End/Sideswipe Total 0.800 0.076 Before-after PHB Pedestrian 0.453 0.167 Median from two studies PHB + Advanced YIELD or STOP Markings and Signs Pedestrian 0.432 0.134 Median from two studies Total 0.820 0.078 Before-after Rear-End/Sideswipe Total 0.876 0.111 Before-after RRFB Pedestrian 0.526 0.377 Cross-section

Summary 3 • FHWA CMF Clearinghouse; • FHWA Proven Safety Countermeasures website; • NCHRP Report 600: Human Factors Guidelines for Road Systems, Second Edition (68); • Manual on Uniform Traffic Control Devices (MUTCD) (62); and • Design guidance for uncontrolled pedestrian crossings. At the end of this report, specific details are provided on how the study results can best be incorporated into each of these guides. As with any proposed safety improvements, it should be remembered that countermeasure selection is a case-specific process, so safety treatments should be based on the specific safety problems and site conditions of the pedestrian loca- tion and not just based on the treatment with the best overall CMF.

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TRB's National Cooperative Research Program (NCHRP) Report 841: Development of Crash Modification Factors for Uncontrolled Pedestrian Crossing Treatments quantifies the safety benefits of four types of pedestrian crossing treatments—rectangular rapid flashing beacons, pedestrian hybrid beacons, pedestrian refuge islands, and advanced YIELD or STOP markings and signs—and presents a crash modification factor (CMF) for each treatment type. This information, which is suitable for inclusion in the American Association of State Highway and Transportation Officials (AASHTO) Highway Safety Manual, the U.S. Federal Highway Administration's (FHWA's) CMF Clearinghouse, and other guidance, will be valuable to transportation agencies in choosing the appropriate crossing treatment for uncontrolled pedestrian crossings.

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