Pedestrian Safety Relative to Traffic-Speed Management (2019) / Chapter Skim
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Pages 13-43
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13 This chapter presents findings from a literature review of countermeasure effectiveness with regard to pedestrian safety and traffic-speed management. Although studies explicitly documenting countermeasure effectiveness with regard to pedestrian safety are still uncommon, many studies have examined how countermeasures work to reduce traffic speed.
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14 Pedestrian Safety Relative to Traffic-Speed Management Figure 2-1. Pedestrian severe injury risk and driver field of vision and stopping distance at various speeds.
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Literature Review 15 struck by light trucks (i.e., pickup trucks, vans, and sport utility vehicles) in his dataset, whereas Rosén and Sander (2009)
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16 Pedestrian Safety Relative to Traffic-Speed Management such as reports from government entities. Throughout this chapter, the terms "countermeasure" and "treatment" are used synonymously.
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Literature Review 17 segment to reduce driving speeds in a residential area. Thus, a summary of existing literature on the impacts of combinations of treatments is presented following the section on the individual treatments.
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18 Pedestrian Safety Relative to Traffic-Speed Management The effectiveness of these treatments to reduce vehicle speeds is well documented. In general, speed humps and speed lumps have been found to be similarly effective, with the latter preferred along emergency response vehicle routes.
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Literature Review 19 similarly and were associated with 50th and 85th percentile speeds 12 mph lower than the roadway with regular marked crosswalks. To date, there is little research on the impact of this treatment directly on pedestrian safety.
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20 Pedestrian Safety Relative to Traffic-Speed Management Agerholm et al.
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Literature Review 21 Ewing's (1999) review of 45 sites across the United States found that 85th percentile speeds reduced by an average of 4 mph after traffic circles were installed.
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22 Pedestrian Safety Relative to Traffic-Speed Management Corkle et al.
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Literature Review 23 which experienced a reduction in average daily traffic (ADT) volumes (SDOT 2010)
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24 Pedestrian Safety Relative to Traffic-Speed Management crash severity at some intersections in New York City, but a CMF has not yet been developed. However, the treatment is considered effective enough for many cities to use it as a key element of slowing driver speed.
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Literature Review 25 Curb Radius Reductions. Curb radius reductions require drivers to make sharper turns and, ideally, drive slower when turning a corner (see Figure 2-11)
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26 Pedestrian Safety Relative to Traffic-Speed Management zone. High-risk conflicts included those with a PET of less than 1 sec, medium-risk conflicts had a PET between 1 and 3 sec, and low-risk conflicts had a PET between 3 and 5 sec (Zangenehpour et al.
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Literature Review 27 More recently, a gateway strategy using these in-street signs (three R1-6 signs placed in the street perpendicular to the direction of travel) has been tested.
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28 Pedestrian Safety Relative to Traffic-Speed Management Also in Cambridge, a combination of curb extensions, a raised crosswalk, and a raised intersection was constructed along Granite Street, a neighborhood collector with a speed limit of 30 mph. The City conducted a speed study before and after the installation of the engineering treatments and found that vehicle volumes remained consistent, 85th percentile speeds decreased from 28 to 24 mph, and the percentage of vehicles traveling above 25 mph decreased from 39% to 14% (Zegeer et al.
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Literature Review 29 school. The treatments included speed humps, edgelines, two raised crosswalks, curb extensions, and a road diet for one street.
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30 Pedestrian Safety Relative to Traffic-Speed Management locations indicated that the percentage of speeding and top-end speeding drivers decreased by 47% to 61% and 71% to 92%, respectively (Vision Zero Network 2018)
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Literature Review 31 sites, respectively. The results of the driver survey indicated that more than half (62%)
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32 Pedestrian Safety Relative to Traffic-Speed Management implemented after a thorough review of the factors contributing to speeding (e.g., roadway design) in order to have the greatest chance of success.
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Literature Review 33 2.2.5 Policies, Programs, and Legislative Efforts Jurisdictions can implement various policies and programs to reduce vehicle speeds and increase pedestrian safety. Each of the strategies listed below will be briefly discussed in this section.
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34 Pedestrian Safety Relative to Traffic-Speed Management slower speeds. After comparing before–after data at neighborhood slow zones and control sites, Hagen (2018)
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Literature Review 35 Systemic Approaches to Reducing Speed Limits. In addition to reducing speeds in designated areas, some jurisdictions are taking a citywide approach by setting new speed limits based on roadway function or class.
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36 Pedestrian Safety Relative to Traffic-Speed Management camera programs (Insurance Institute for Highway Safety 2018) , although only 16 states and the District of Columbia allow them (see Figure 2-19)
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Literature Review 37 speeds and improve pedestrian safety. Although most of the evaluations discussed did not measure changes in vehicle–pedestrian crashes, the notable reductions in vehicle speeds indicate that these programs can improve pedestrian safety by reducing the likelihood of a crash in the first place and the likelihood of a severe injury in the event that a pedestrian is struck by a vehicle.
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38 Pedestrian Safety Relative to Traffic-Speed Management Two key elements of Vision Zero and other Safe System approaches are the understanding of the human body's vulnerability and the fact that people, no matter how well intentioned, make mistakes. Based on this understanding, a Safe System approach to roadway safety seeks to minimize opportunities for human error that could lead to fatalities and severe injuries.
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Action Type of Action Vision Zero Action Plan Create 25 new arterial slow zones. Engineering New York City (2014)
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40 Pedestrian Safety Relative to Traffic-Speed Management Achieving Vision Zero. Only a few cities have been pursuing Vision Zero long enough to have data to evaluate their efforts; of those, demonstrable reductions in pedestrian crashes have been documented in New York City and San Francisco.
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Literature Review 41 speed humps and speed tables, are generally considered the most effective. These are followed by treatments with horizontal deflection, such as chicanes and traffic circles.
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Countermeasure Type Effectivenessa Roadway Context Safety Benefit Referencesb Notes Speed humps Engineering (vertical deflection) Proven Local/low-speed collectors CMF for vehicle- pedestrian crashes: 0.45 to 0.74 Ewing 1999; Tester et al.
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Curb radius reduction Engineering Promising Arterials/higher-speed roads May reduce speeds Thomas et al. 2016 -- Speed-limit reduction Policy Promising All May reduce injury severity and mean speeds Leaf and Preusser 1999; Rosén and Sander 2009; Tefft 2013 Potentially low effectiveness when used alone; better complemented by physical design changes Neckdowns/ bulb-outs/ curb extensions/ chokers Engineering (horizontal deflection)
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