Safety in Numbers: Models of Pedestrian and Bicycle Crash Frequency and Severity at Signalized Intersections in Utah Using Innovative Measure of Exposure

Recent trends indicate a dramatic increase in both the number and share of pedestrian and bicyclist injuries and fatalities nationally and in many states. This study aimed at understanding (geometric, traffic, operational, and other) factors associated with pedestrian and bicycle safety and also to assist in the prioritization and selection of counter measures to improve pedestrian and bicycle safety at signalized intersections. Several negative binomial models were estimated to investigate factors affecting pedestrian and bicycle crash frequency. The models suggested several characteristics of the road network, land use, built environment, and neighborhood sociodemographics were significantly associated with more (or fewer) pedestrian and bicycle crashes. Ordered logit models were fitted to investigate factors affecting injury severity in pedestrian and bicycle crashes. The model results indicated that vehicle size, vehicle maneuvering direction, and involvement of teenage/older drivers and DUI/drowsy/distracted driving in crashes had significant effects on injury severity in pedestrian and bicycle crashes. The study also found strong support for the “safety in numbers” effect, in which pedestrian/bicycle crash rates decrease with an increase in pedestrian/bicycle volumes

Improving Intersections for Pedestrians and Bicyclists Informational Guide

DTFH61-16-D-00005Intersections are critical points of access to local and regional destinations for all roadway users. When designed with pedestrians and bicyclists explicitly in mind, all types of intersections can facilitate safe, accessible, convenient, and comfortable walking and bicycling. The purpose of this guide is to inform the state of the practice concerning intersection planning and design to implement solutions that help achieve the goal for zero fatalities and serious injuries while improving mobility for bicyclists and pedestrians. The primary intersection types discussed in this guide include traditional signalized intersections, roundabouts, Median U-Turn (MUT) intersections, Reduced Crossing U-Turn (RCUT) intersections, Quadrant Roadway (QR) intersections, Displaced Left Turn (DLT) intersections, and Diverging Diamond Interchanges (DDI). This guide also includes discussion about stop-controlled and uncontrolled intersection crossings for bicyclists and pedestrians. This guide illustrates integration of bikeways and pedestrian pathways at and across traditional and alternative intersections, describes countermeasures applicable to pedestrian and bicyclist crossings at intersections, and summarizes the application of intersection analysis methods for the safety and mobility of pedestrians and bicyclists. This guide serves as a supplement to the Federal Highway Administration\u2019s (FHWA\u2019s) series of intersection informational guides and makes direct connections to other FHWA bikeway and pedestrian facility selection guides. Part I presents three foundational principles for planning and designing intersections for pedestrians and bicyclists. Part 2 presents design concepts for each of the intersection types discussed in this guide and illustrates options and design flexibility for incorporating a variety of pedestrian and bicycling facility types. This guide is intended to supplement, but not replace, design guidance, traffic control standards, and countermeasure selection criteria

Planning methodology for alternative intersection design and selection

The recent publication of the 6th Edition of the Highway Capacity Manual included a chapter on Ramp Terminals and Alternative Intersections that introduces various alternative intersection designs and assesses the performance of Median U-turn, Restricted crossing U-turn and Displaced left-turn intersections. Missing from the literature is an alternative intersection selection tool for identifying whether an alternative intersection would be successful under local conditions. With limited information of organized alternative intersection research, most planners must rely heavily on their personal judgement while selecting the most suitable intersection designs. As appealing as alternative intersections are, there is no comprehensive methodology for planners to evaluate all possible designs and locate the best option. Several studies have been performed on identifying the selection of the most appropriate alternative intersection. As straightforward as they are, they failed to accommodate the Highway Capacity Manual (HCM) and are highly dependent on the professional judgment of the planners. This dissertation aims to design a selection methodology that is easy to use and HCM compatible and independent of personal judgments. The selection procedure is composed of three stages. The goal of the first stage is to clarify the objectives and concerns of planners in the selection of candidate intersections. This stage should identify the treatment objectives (for existing intersections) and stakeholders’ concerns (for new intersections). If more than one objective were identified, the planners should assign a weight for each objective. A questionnaire should be used in collecting this information. The second stage is to filter out some candidate designs before the detailed analysis. This stage tries to generalize the range of application for each Unconventional Alternative Intersection Design (UAID). Any design that cannot satisfy the capacity and Right-of-Way (ROW) requirement is deleted from future analysis. In stage three of the selection process, the alternative intersection designs selected for consideration are ranked and assessed based on the treatment purposes/stakeholders’ interests, which may likely include increasing mobility or safety. By identifying a primary parameter used to score or rank all the considered intersections, the alternative intersection selection tool would assist planners to compare different intersection designs and to describe the intersection performance comprehensively. The primary parameter should account for both mobility and safety at each of the intersections evaluated. For intersection mobility, the evaluation process relies on methodologies provided in the Highway Capacity Manual 2016. For the safety assessment, a safety evaluation procedure is also developed to provide an overall assessment of the safety performance at the evaluated intersection. A selection algorithm is then designed to rank all intersections based the intersection performance

Planning-Level Guidelines for Modern Roundabouts, 2008

This technical memorandum provides preliminary planning-level guidance to engineers, technicians, planners, and policymakers who may be considering a modern roundabout at an existing or proposed intersection in Iowa

Development of Performance Matrices for Evaluating Innovative Intersections and Interchanges [MPC-19-391]

MPC-465Innovative intersections and interchanges have proliferated in the State of Utah over the past several years. Continuous flow intersections and diverging diamond interchanges seem to offer improved traffic performance and safety due to their innovative designs. However, there are no clearly defined guidelines or methodologies for monitoring and measuring their performance. Yet, they have a broad impact on operations, safety, access, transit, land use, economic development, and pedestrian and non-motorized traffic. Due to these numerous and overlapping variables, there is a need to develop a standard methodology to further evaluate innovative designs with regards to different performance measures. The goal of this research is to develop a matrix of performance measures, which can be applied in practice to effectively evaluate innovative designs in terms of operations, safety, access, and multimodal accommodations. The study develops and tests an Excel-based tool for evaluation and comparison of different conventional and innovative designs. The tool is based on the existing methodologies and those currently being developed, and they provide analyses of these designs for different performance measures, such as operational, safety, transit and non-motorized user performance, access, and user costs. It can be used for planning, designing, and monitoring performance of innovative designs

Visual Approaches to Understanding Pedestrian Safety in Roundabouts

Although road safety research has traditionally considered driving as the central mode of interest, recent work has turned to non-motorized modes, particularly cycling and walking, to analyze their conditions within traffic flow, and their interaction with vehicles. �Visual Approaches to Understanding Pedestrian Safety in Roundabouts� is a thesis developed by Mario Perdomo where pedestrian safety is targeted as the main object of study. The research includes two separate studies. The first, based on a Stated Preference (SP) research tool, aims to describe the preferences of pedestrians towards design and operational features of roundabouts, an intersection whose construction has become more frequent in recent years in Quebec. This study describes the process of designing, administering and analyzing the SP survey, offering as its main outcome relevant conclusions regarding pedestrian preferences in terms of safety in roundabouts. The use of substitution rates, estimated from the analysis of the SP survey, are suggested as a means to help guide the design of roundabouts with pedestrians in mind. The second study examines pedestrian-vehicle interactions in roundabouts using automatic pedestrian and vehicle tracking with videos. These interactions were analyzed, making it possible to observe actual pedestrian behavior in such intersections. The core of the thesis relies on two scientific papers: one published in Accident Analysis and Prevention journal in 2014; and the other submitted to the Transportation Research Board the same year

Modeling pedestrian safety at roundabouts

This study proposes a method for using a human participant in a field experiment to model pedestrian safety at roundabouts in the United States. Studies show that roundabouts are safer for vehicles, but are inconclusive as to whether pedestrians are at greater risk at roundabouts than at signalized intersections. Recent simulations, including virtual reality, can model pedestrian vehicle interaction, but the proposed technique could use real-world data to calibrate these models. Eight hours of video was made to gather data at a signalized intersection and a roundabout. A physical simulation was used to assess the pedestrian’s cross/don’t cross decision. Standard walking pace was simulated at 3.5 feet per second and a disabled pedestrian at half that pace. This study focused on factors such as signalization, approach streams, exit vs. entrance lanes, pace and direction to provide a realistic picture of the cross vs. don’t cross decision. Data showed that slow pedestrians had a significantly higher rate of don’t cross decisions at the roundabout. Roundabouts are thought to be safer for pedestrians than signalized intersections due to a lower number of conflict points, but the confusing multiple streams of roundabout traffic converging on exit lanes and the frames of approaching traffic at roundabout entrances may mean that another concept may be needed to fully capture pedestrian risks. The data on ‘relevant traffic’ showed that pedestrians had to be attentive to almost six times as many approach streams of traffic in the roundabout as in the signalized intersection. The value of this study is four-fold: 1) Future studies could revisit the conflict point at the core of Traffic Conflict Analysis and consider conflict streams as well; 2) Future studies could consider the cross/don’t cross decision as an important data point with which to evaluate the safety of roundabout crossings; 3) Slow pedestrians fared worse in their ability to cross at the roundabout than at the signalized intersection; 4) The human participant in a field experiment method can be a valuable source of data for calibrating pedestrian safety simulation systems

Modeling pedestrian safety at roundabouts

This study proposes a method for using a human participant in a field experiment to model pedestrian safety at roundabouts in the United States. Studies show that roundabouts are safer for vehicles, but are inconclusive as to whether pedestrians are at greater risk at roundabouts than at signalized intersections. Recent simulations, including virtual reality, can model pedestrian vehicle interaction, but the proposed technique could use real-world data to calibrate these models. Eight hours of video was made to gather data at a signalized intersection and a roundabout. A physical simulation was used to assess the pedestrian’s cross/don’t cross decision. Standard walking pace was simulated at 3.5 feet per second and a disabled pedestrian at half that pace. This study focused on factors such as signalization, approach streams, exit vs. entrance lanes, pace and direction to provide a realistic picture of the cross vs. don’t cross decision. Data showed that slow pedestrians had a significantly higher rate of don’t cross decisions at the roundabout. Roundabouts are thought to be safer for pedestrians than signalized intersections due to a lower number of conflict points, but the confusing multiple streams of roundabout traffic converging on exit lanes and the frames of approaching traffic at roundabout entrances may mean that another concept may be needed to fully capture pedestrian risks. The data on ‘relevant traffic’ showed that pedestrians had to be attentive to almost six times as many approach streams of traffic in the roundabout as in the signalized intersection. The value of this study is four-fold: 1) Future studies could revisit the conflict point at the core of Traffic Conflict Analysis and consider conflict streams as well; 2) Future studies could consider the cross/don’t cross decision as an important data point with which to evaluate the safety of roundabout crossings; 3) Slow pedestrians fared worse in their ability to cross at the roundabout than at the signalized intersection; 4) The human participant in a field experiment method can be a valuable source of data for calibrating pedestrian safety simulation systems

Designing and Implementing Maintainable Pedestrian Safety Countermeasures

(c) 1036334 (wo) 6While pedestrian safety countermeasures contribute to reducing vehicle-pedestrian crashes, their impacts on winter maintenance operations are sometimes overlooked during design. There is a need to investigate the best practice guidance and solutions for the design, installation and maintenance of pedestrian safety features for year-round maintenance. To address this, we conducted a search of literature as well as agency interviews to identify and document current best practices for designing and implementing pedestrian safety countermeasures for year-round maintainability. The countermeasures reviewed included curb ramps, crosswalk markings, corner radii, curb extensions, refuge islands, and speed humps and raised crosswalks. The information collected allowed for the development of conclusions and recommendations for these features. The design dimensions and features of pedestrian curb ramps are established by the Americans with Disabilities Act and should have a slope of greater than 1:12 and a maximum cross slope of 1:50. Durable materials can be used for crosswalk markings, and these can be grooved into the pavement to provide protection from abrasion. Bulb-outs should use a 1:2 or 1:3 upstream taper and a 1:3 downstream taper. When used, tight radii of 15 feet or less should be employed. Refuge islands can range from 6 feet or greater in width, 24 feet to 40 feet in length, with a 4-foot or greater walkway width. Finally speed humps and tables should be between 3-4 inches in height, with lengths of 12-14 feet (humps concave in shape) and up to 22 feet (tables)