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Suggested Citation:"Chapter 1 - Project Overview." 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:"Chapter 1 - Project Overview." 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 5

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4C H A P T E R 1 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. Further- more, there is a need to better understand the safety effects of some of the more promising treatments. Numerous studies have been conducted in the United States and abroad in recent years on the effects of various geometric and traffic control treatments at unsignalized cross- ings. However, most of those evaluations have relied on behavioral and operational measures of effectiveness (e.g., pedestrian/vehicle conflicts, vehicle speeds, and driver yielding behavior) instead of crashes as the measure of effectiveness. The lack of crash-based evaluations for such pedestrian treatments results largely from sample size issues, that is, pedestrian crashes usually do not cluster to the same degree at specific sites, so a larger number of treatment and compari- son sites may be needed to obtain sufficient statistical power to detect a change in crashes due to the treatment, compared to the evaluation of countermeasures for vehicle/vehicle crashes, which occur at a higher frequency. Thus, there is a need to conduct evaluations over a wider region and over a longer time period in order to obtain an adequate sample size to allow for the development of crash modification factors (CMFs) or Functions (CMFunctions) that can provide guidance as to the most effective pedestrian crossing treatments to use. This project sought to develop CMFs for selected pedes- trian crossing treatments for various traffic and roadway conditions, to the extent possible. An attempt was made to develop CMFunctions that would allow a CMF to be estimated based on specific site conditions. The original objective of this project was to develop CMFs for several different types of pedes- trian treatments at unsignalized pedestrian crossings. Candidate treatments that were consid- ered for possible evaluation in this study were the following: • Unsignalized pedestrian crosswalk signs and pavement markings, including advanced YIELD or STOP markings and signs; • Pedestrian hybrid beacons (PHBs); • Rectangular rapid flashing beacons (RRFBs); • Pedestrian refuge islands; • Curb extensions; • In-pavement warning lights; • High-visibility crosswalk marking patterns; and • Raised crosswalks. Of the potential candidate treatments listed above, it was not possible to find a sufficient sam- ple of sites with raised crosswalks and/or in-pavement warning lights to develop reliable CMFs. Also, consideration was given to selecting treatments for evaluation that were thought to be of particular interest to local and state traffic and safety officials. Finally, available project funds and Project Overview

Project Overview 5 the importance of each treatment in terms of CMF development were taken into consideration in choosing treatments for evaluation. Ultimately, four treatments were selected for evaluation: • RRFBs • PHBs • Pedestrian refuge islands • Advanced YIELD or STOP markings and signs The selection of these four treatments (see Appendix A for descriptions of the treatments) was approved by the project panel. Data were collected for locations having one of these treat- ments and for appropriate non-treated comparison (reference) sites. Some of the treatment sites selected for field study had more than one of these four treatments. The study sampling was focused on sites on multi-lane, high-volume roads, since these are the types of sites where pedestrians are at the greatest risk, and therefore, where there is a greater need for the types of countermeasures evaluated in this study. Data collection efforts included following: • Identifying suitable treatment and comparison sites for analysis; • Collecting basic site characteristics data at select sites; • Collecting pedestrian count data at the treatment and comparison sites for use in computing estimated pedestrian average annual daily traffic (AADT); • Collecting vehicle AADT numbers at the treatment and comparison sites; and • Collecting crash summaries for pedestrian and total crashes.

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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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