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4 1.1 Background This project aims to document strategies and tools that address pedestrian safety via traffic- speed management. The time is ripe for understanding the nexus between these two areas, as thou- sands of pedestrians are killed by motor vehicles annually in the United States, including nearly 6,000 in 2016 alone (NHTSA 2018), and hundreds of thousands more are injured. Moreover, these numbersâboth as a whole and as a percentage of all traffic fatalitiesâhave been increasing in recent years, despite motor-vehicle fatalities experiencing a general decline over time (Insur- ance Institute for Highway Safety 2018). These traffic collisions take an extraordinary monetary and emotional toll on society, the communities in which they occur, and the individuals involved. At the same time, vehicle speed is increasingly identified as contributing to traffic risk. The National Transportation Safety Board (2017) found that vehicle speed was a contributing factor in over 30% of traffic fatalities from 2005 to 2014. Transportation researchers and professionals generally agree that lowering driver speed influences collision severity (RosÃ©n and Sander 2009, Tefft 2013, NTSB 2017) and the overall likelihood of a collision (Elvik et al. 2004, Aarts and Schagen 2006, NTSB 2017). Communities in other parts of the world routinely achieve much stronger records for overall safety and pedestrian safety compared to communities in the United States. For example, the Vision Zero approach (explained in Section 1.1.1) was conceived in 1994 and adopted into official Swedish policy in 1997 (Vision Zero Initiative n.d.). Figure 1-1 demonstrates Swedenâs progress toward reducing traffic fatalities since that time, showing a strong reduction in traffic fatalities per million people (3.9% average annual decrease). Although the United States has also experienced a large reduction, it has not been nearly as dramatic (1.7% average annual decrease): It is estimated that up to 15,000 lives in 2015 alone could have been saved if the United States had pursued safety as aggressively as Sweden over the last three decades. Research comparing pedestrian safety in the United States to 10 peer countries found that while all countries made progress in reducing pedestrian fatality rates per capita from 1990 to 2014, the United States made the least progress, falling 35% (Pucher and Buehler 2017; see thick solid line at the top of Figure 1-2). In contrast, Denmark and Sweden made the most progress: Western European countries reduced their pedestrian fatality rate by 68% in the same period. Looking at more in-depth data for the United States and Germany from 2000 to 2001 and 2008 to 2009, Pucher and Buehler found that pedestrian fatality rates were significantly higher in the United States than in Germany in both survey periods and for all age groups. For the popula- tion as a whole, pedestrian fatality rates in the United States were about five times higher than those in Germany during the 2008 to 2009 period. These rates were also estimated to be significantly lower for other countries such as the Netherlands, Denmark, and the United Kingdom. C H A P T E R 1 Introduction
Introduction 5 0 20 40 60 80 100 120 140 160 180 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 Fa ta liti es p er 1 ,0 00 ,0 00 p op ul ati on USA - Actual Sweden If the USA had followed Sweden Figure 1-1. Fatalities per million population in the United States and Sweden, 1995â2015. (Data source: Fatality Analysis Reporting System; Vision Zero Initiative; Image source: Toole Design.) 0 10 20 30 40 50 60 70 80 90 100 1990â1994 1995â1999 2000â2004 2005â2009 2010â2014 Pe rc en t R el ati ve to 1 99 0- 19 94 United States Australia Japan Canada United Kingdom Netherlands Germany France Spain Denmark Sweden Figure 1-2. Trend in pedestrian fatality rate per 100,000 population 1990â2014, 5-year annual averages relative to 1990-1994 average. [Note: For comparison, the 1990â1994 average was set at 100%. Source: Pucher and Buehler 2017, based on Organisation for Economic Cooperation and Development (OECD) data; Image modified by Toole Design.
6 Pedestrian Safety Relative to Traffic-Speed Management Key to these countriesâ success is a shift in thinking about traffic safety. The United States has tended to view safety in a narrower and more reactive way, placing almost complete responsibility for collisions on the people involved, and identifying and treating crash hot spots after they have occurred. In contrast, many other countries are following a Safe System approach that acknowledges more clearly the role of infrastructure on behavior, as well as the need for a system to be forgiving when someone makes a mistake. The Safe System approach, therefore, places the responsibility for safety on multiple parties, including system designers, policy makers, and engineers. While those ultimately involved in a collision still have responsibility, a core tenet of the Safe System approach holds that crash prevention starts at roadway conceptualization and that roadway design and attending policies are key to achieving the type of safe behavior that ultimately results in fewer crashes, particularly fewer serious crashes. Another core tenet of the Safe System approach recognizes that the human body can with- stand only a certain amount of impact before serious injury or death results. Because the kinetic energy behind the impact is directly related to vehicle speed, speed is critically related to injury severity and must therefore be limited in areas where pedestrians are expected, if pedestrian safety is prioritized. Speed can be limited through various strategies, including initial roadway design, countermeasures, enforcement, and education. The Safe System approach is best known in the United States under the name Vision Zero. Vision Zero is a movement coalesced around the idea that serious and fatal traffic injuries are largely preventable and that our communities can and should do more to eliminate them. As of January 2018, 34 cities in the United States had committed to becoming Vision Zero cities, and several cities were in the midst of efforts that had been underway for 2â3 years. Although the literature on speed reduction specifically to address pedestrian safety is thin, these Vision Zero cities have been trying to directly address the problem and therefore provide informative case examples to study. Because of their particular focus in this area, these Vision Zero cities, and cities with similar efforts, receive a spotlight in this report. 1.2 Objectives The objective of this synthesis is to provide an understanding of current research and practice related to efforts to improve pedestrian safety via traffic-speed management in urban environments. The synthesis is intended to be useful to transportation agencies and policy makers in selecting and implementing strategies to improve pedestrian safety. This synthesis is not intended to be an exercise in and does not cover crash-data collection and analysis; for more information on those topics, see NHTSAâs Community-Based Bicycle and Pedestrian Safety Assessment Tool (in progress); NCHRP Project 17-73, âGuidance on Systemic Pedestrian Safety Analysesâ (Thomas et al. 2018); and other related NCHRP guidance. Additionally, this synthesis focuses on practices relevant to the United States. Therefore, noteworthy international examples are included only when relevant examples from the United States were unavailable. The report contains the following information: â¢ A literature review exploring how speed is related to pedestrian injury severity and describing a range of countermeasures known to be effective at reducing speed; and â¢ A synopsis of interviews with cities that have implemented key pedestrian safety policies related to vehicle speed (mostly, but not exclusively, Vision Zero cities), including information about â Noteworthy examples of actions taken and countermeasures implemented to achieve speed reduction and improve pedestrian safety in these cities (e.g., design, enforcement, educa- tion, operations, and public engagement);
Introduction 7 â Performance metrics and the evaluation of speed-reduction actions on pedestrian safety; â Barriers to reducing speed and potential work-arounds for interested jurisdictions; and â Lessons learned from these jurisdictionsâ efforts. A final synopsis of the information, including identified gaps in understanding and sugges- tions for future research, concludes the report. 1.3 Synthesis Scope and Approach In order to provide a comprehensive understanding of the state of knowledge around pedes- trian safety relative to traffic-speed management, this project took a mixed-methods approach composed of a literature review and in-depth interviews. 1.3.1 Literature Review The literature review paints a picture of what is known about how to improve pedestrian safety via traffic-speed management. Though it would have been ideal to cover only literature that examined specifically how countermeasures reduce speed and ultimately impact pedestrian safety, few studies have focused on pedestrian impacts from speed-reduction efforts. Rather, most studies on countermeasures implemented to reduce speed focus on how effectively they do so. Thus, the literature review begins with a section covering the relationship between speed and pedestrian safety. This section is followed by sections on the effectiveness of various types of countermeasures with regard to reducing vehicle speed, insights into regulatory barriers to reducing speed, and contributions of the Vision Zero movement to the overall discussion of speed and pedestrian safety. The literature review was conducted by searching for academic and gray literature (i.e., reports produced by government agencies) regarding speed reduction and pedestrian safety in particular, pedestrian safety/injury severity and speed, countermeasures to reduce speed more generally, and efforts to address pedestrian safety via traffic-speed management among Vision Zero cities. Search engines included Google Scholar and TRID. When relevant resources were found, their bibliographies were explored for additional relevant resources. Appendix A includes an annotated bibliography of the referenced sources. 1.3.2 Screening Survey and Interviews A key part of understanding the state of practice with regard to pedestrian safety and traffic- speed management involved talking to the agencies at the vanguard of the effort. The following sections on the screening survey and interviews describe the efforts made to contact and inter- view these jurisdictions to learn more about their work. Screening Survey Although the panel discussed a focus on Vision Zero cities, it was recognized that cities and counties might be addressing pedestrian safety and traffic speed via other means. For this reason, the project team elected to conduct a screening survey to learn about safety efforts similar to, but not called, Vision Zero. The team developed a short online survey and, in February 2018, sent a link in an email invitation to listservs for the Association of Pedestrian and Bicycle Professionals, ITE, and ASCE, as well as to a list of over 2,000 contacts from jurisdictions throughout the United States that is maintained by the project team. Email reminders were sent twice, approxi- mately 1 week apart, to encourage participation in the survey.
8 Pedestrian Safety Relative to Traffic-Speed Management Because the focus of the practitioner-based portion of the synthesis focuses on evidence to the extent possible, the survey asked specifically for jurisdictions that are working on pedestrian safety and speed and have either measured their efforts and can draw some kind of conclusion or are explicitly committed to Vision Zero (Appendix B includes a copy of the survey). These bounds limited the number of valid respondents to 33. This small number was not unexpected, given the relatively small number of Vision Zero cities and the even smaller number of Vision Zero cities that have been working long enough to have results to share. Additionally, not everyone who responded to the survey was willing to be interviewed, and not all were far enough along in their efforts to have evidence-based results that could inform this project. After examining the survey responses, 12 jurisdictions were selected for an interview. Interviews The 12 jurisdictions identified for interviews were contacted and agreed to participate in an hour-long, semiscripted interview (the script is located in Appendix C). Semiscripting the interview allowed the project team to ensure that certain information was gleaned from each conversation, but also provided some space for the interviewees to bring in related information as opportunities arose. Questions pertained to the types of efforts the agencies were employing to address pedestrian safety via traffic-speed management, key partners in their efforts, commu- nity resistance and how it was addressed, relationships with state DOTs, barriers to managing speed, and lessons learned from their experiences. Notes were taken during the interviews, and the interviews were digitally recorded (with per- mission) so that information could be double-checked during the subsequent write-up. To orga- nize the findings from the interviews, the project team developed a coding scheme to represent major and minor themes, which are detailed in Chapter 3. The team also sought examples of noteworthy practices to share; these are highlighted separately in sidebars in the chapter. On reflection, one of the interviewed cities was not nearly as far along as the other cities in their efforts; therefore, this city is not profiled in this report. Summaries of each of the 11 remaining jurisdictionsâ interviews are presented in Appendix D. Occasionally, agency representatives sent materials for the project team to review that supplemented the information discussed during the interviews. Where applicable, findings from these materials are referenced in either Chapter 2 (Literature Review) or Chapter 3 (State of the Practice) of this report. In addition, all sidebars within Chapter 3 are specific to topics discussed in interviews. 1.3.3 Gaps in Understanding This synthesis provides a foundation on which to build additional understanding about how to improve pedestrian safety via traffic-speed management. The literature review and inter- views revealed several effective countermeasures for reducing speed on local roads, although additional research is needed to understand how these countermeasures differ specifically with regard to pedestrian safety. There is also a need for additional solutions for higher-volume, higher-speed roadways in urban areas like arterials, which tend to be the locations of the most injurious crashes for pedestrians and overall. Although some countermeasures appropriate for arterials have been developed, they are often prohibited by state laws [e.g., automated speed enforcement (ASE)] or local policies (e.g., speed humps), or they are politically difficult to implement (e.g., street reconfigurations). Political difficulty and the lack of legality relate to a core issue with traffic- speed management: When people are accustomed to, and even depend on, driving a fairly high
Introduction 9 speed to go about their daily lives, a culture of high speed and auto dependence results. Thus, in addition to the need for speed-reduction solutions on these higher-volume, higher-speed roadways, there is a need for future research regarding facilitating behavior and culture change related to speed and auto dependence, which this synthesis addresses. Finally, the interviews revealed a lack of clarity about how speed limits are ultimately set and therefore how they can be changed. Relatedly, there emerged a desire for a framework that can foster intra-agency collaboration when working to address traffic safety via traffic-speed management. These and related research needs are elaborated on in Chapter 4. 1.3.4 Considerations when Using this Synthesis This synthesis reflects a relatively new, albeit critically important, focus of the transporta- tion profession unlike other practice areas for which much research has been conducted. For this reason, the literature review addresses speed in a roundabout way; the survey did not have a large number of respondents; and the interviewees reflect agencies at the vanguard of the effort, as opposed to a more ideally geographically dispersed, diverse set of responses. Additionally, some of the agencies profiled in this project have not been directly addressing traffic speed long enough to have robust or statistically significant results to share. Therefore, some of the synthesis reflects practices that are considered promising rather than proven. With that said, it is hoped that the contents of this synthesis will provide a slate of proven and promising options for addressing speed, resources for working with other agencies to co-develop and test additional solutions, and inspiration for creatively working within confines to achieve the goal of substantially safer pedestrian travel throughout the United States. 1.4 Terminology In general, this synthesis has been written to avoid jargon and explain terms and concepts in common language. However, the following few terms and concepts merit definition in order to ensure that readers are considering them consistently. 1.4.1 Key Terms 85th percentile speedâa speed at or below which 85% of all vehicles are observed to travel under free-flowing conditions. Average/mean speedâthe average of individual vehicle speeds on a specific roadway. Complete Streetsâa transportation policy and design approach that aims for streets to be planned, designed, and operated safety and conveniently by all users, regardless of their age, ability, or chosen means of travel. Countermeasureâa treatment or action designed to offset an undesirable action (for the purposes of this synthesis, the undesirable action is driving at a speed above the posted speed limit: speeding). âCountermeasureâ and âtreatmentâ are used interchangeably. Fatal injury or fatalityâan injury that results in death. High-crash corridors/high-injury networkâa set of roadways within a jurisdiction that are historically the locations of the most serious and fatal crashes. High speedâ35 mph or greater. See âlow speedâ for justification of 35 mph as appropriate definition of high-speed roads when used in the context of pedestrian safety planning.
10 Pedestrian Safety Relative to Traffic-Speed Management Low speedâ30 mph or less. Definitions of low-speed roads vary, and some federal sources define low speeds as those below 45 or 50 mph (FHWA 2005; AASHTO 2011), however, these lower speeds are not considered safe or appropriate for environments where pedestrian activity is expected. NCHRP Report 737: Design Guidance for High-Speed to Low-Speed Transition Zones for Rural Highways recommends reducing speed limits to 30 mph in areas where highways run through communities where pedestrian activity may be expected (Torbic et al. 2012). As such, this synthesis defines low-speed roads as those with posted speeds of 30 mph or less. Operating speedâthe speed at which motor vehicles generally travel on a specific roadway. Posted speedâthe maximum speed limit posted for the roadway, posted on regulatory signs along the roadway. Safe System approachâan international approach to road safety management that focuses on building safety in at a systemic level, rather than retrofitting spot locations after crashes have occurred. This approach is based on the principles that safety should not be compromised by the need to travel; that humans make mistakes, but the system should not; and that humans can tolerate only a certain amount of impact before serious or fatal injuries occur, and thus that the system should be designed for that tolerance. Serious injuryâa life-altering personal injury that results in dismemberment, significant disfigurement, a fracture, or the permanent loss or limitation of a body function. Top-end/high-end speedingâdriving 10 mph or more above the posted speed limit. Toward Zero Deathsâa U.S.-specific strategy for highway safety that aims to eliminate fatalities on roadways. Traffic calmingâthe use of physical design features to slow traffic, make drivers more care- ful, and improve safety for roadway users. Traffic-calming measures are grouped within four categories: vertical deflection, horizontal deflection, lane and road reconfiguration, and signs and signals. Vision Zeroâan international road traffic safety program that aims to eliminate fatalities and serious injuries on roadways. 1.4.2 Countermeasure Definitions Automated speed enforcementâenforcement involves the use of fixed or mobile speed cameras that measure vehicle speeds and photograph vehicles that exceed the speed limit by a predetermined amount. Chicaneâsmall, raised islands used to narrow the roadway and laterally shift traffic. Typi- cally, two or three chicanes are placed within a small area, either on the same side or alternating sides of the roadway. Curb radius reductionâthe act of extending a curb to reduce the corner radius. High-visibility enforcementâtargeted enforcement efforts that are highly publicized to the public. In-street pedestrian crossing signâreferred to in the Manual on Uniform Traffic Control Devices as a Yield to Pedestrian sign (MUTCD R1-6). Lane narrowing with pavement markingsâa traffic-calming treatment that uses only pave- ment markings to narrow the roadway width. No raised treatments or physical changes to edges of the roadway are associated with this treatment.
Introduction 11 Mini traffic circlesâsmall, circular raised islands placed in the middle of uncontrolled inter- sections of residential streets. Neckdowns, bulb-outs, curb extensions, and chokersâraised treatments that physically narrow the roadway width at intersections or in the middle of the block. These treatments can be applied by extending the curb or by adding small raised islands, similar to chicanes. Raised mediansâraised, oval-shaped islands that narrow the roadway width. Pedestrian crossing islandsâraised medians with a cut-through that provides a refuge area for pedestrians at crossing locations. Pedestrian crossing islands must be designed to meet accessibility standards and ideally provide a cut-through that is as wide as the crosswalk. Roadway (or street) reconfigurationâa technique in which the number and/or widths of vehicle lanes are reduced to improve operation, speed, or safety of the roadway. Road recon- figurations are also known as âroad dietsâ or ârechannelizations.â These commonly result in the narrowing or removal of a through travel lane to add a turn lane, bicycle lanes, or medians that can provide pedestrian refuge. Roundaboutsâcircular center islands that move traffic in one direction in a circular manner; speed is controlled upon entry. Roundabouts are typically placed in the middle of uncontrolled intersections of larger streets like collectors or arterials. Speed feedback signsâdynamic signs that display the vehicle travel speed of the nearest approaching vehicle. Speed humpâcontinuous raised pavement area, typically 12 to 14 ft long and 3 to 4 in. high. Speed humps provide more gradual changes in elevation than speed bumps. Speed lump/speed cushionâspeed humps with cutouts to allow wheels of large vehicles (e.g., emergency-response vehicles and buses) to pass through easily. Speed tableâa longer and wider version of a speed hump (typically 22 ft long) that has a flat top and ramps on either side of the raised area to provide a more gradual change in elevation than speed humps. Raised crossingâspeed tables used at designated crossing areas that have crosswalk markings. Speed-activated speed-limit signsâdynamic signs that display the speed limit for an approaching vehicle only if it is travelling faster than a specific, predetermined speed. 1.4.3 Abbreviations AASHTOâAmerican Association of State Highway and Transportation Officials ASEâautomated speed enforcement, a type of enforcement that uses speed cameras, rather than humans, to enforce speed limits and issue citations CMFâcrash modification factor, a factor by which one can expect crashes to change if a countermeasure is installed CTCDCâCalifornia Traffic Control Devices Committee DOTâdepartment of transportation, usually referring to a state in this report FHWAâFederal Highway Administration MUTCDâManual on Uniform Traffic Control Devices; California creates a supplement to the MUTCD known as the CA MUTCD.
12 Pedestrian Safety Relative to Traffic-Speed Management 1.5 Report Organization The remainder of the report is organized as follows: Chapter 2âThis chapter presents findings from the literature review of countermeasures found to be effective in reducing vehicle speed. It also provides an overview of Vision Zero policies in several U.S. cities and discusses regulatory barriers to reducing speed. Chapter 3âThis chapter presents a brief overview of the survey results and then delves into findings from the in-depth interviews. Noteworthy practices are highlighted in sidebars. Chapter 4âThis chapter synthesizes and distills key findings from Chapters 2 and 3. Addi- tionally, this chapter elaborates on gaps in current understanding and suggested research to fill these gaps. ReferencesâThis section lists references used to write this report. Appendix AâThis appendix contains additional information for each of the studies in the literature. Appendix BâThis appendix contains a copy of the screening survey instrument. Appendix CâThis appendix contains a copy of the semiscripted interview instrument. Appendix DâThis appendix contains additional information from each of the case studies.