Intersection Design to Accommodate ADA Curb Ramps: Intersection Design to Address Pedestrian Safety

Rouphail, Cunningham, et al. This study evaluated the performance of pedestrian-bicycle crossing alternatives at Continuous Flow Intersections (CFI). Further, a comparison was also performed of CFI crossing types against a standard intersection designed to provide an equivalent volume-to-capacity ratio. Three CFI crossing alternatives were tested, namely Traditional, Offset, and Midblock crossings. In total, 24 alternative scenarios were generated by incorporating two bicycle path types, two right-turn control types, and two CFI types. These scenarios were analyzed through microsimulation on the basis of stopped delay, travel time, and number of stops. Simulation results revealed the Offset crossing alternative incurred the least stopped delay for all user types. The Traditional crossing generated the least number of stops. The Midblock crossing can be considered as a supplement to either the Offset or Traditional crossing depending on the specific origin-destination patterns at the intersection. The exclusive bicycle path performed better than the shared-use path in most cases. However, these general trends may vary significantly at the route-level analysis. When compared with an equivalent standard intersection, aggregated results showed significant improvement for all CFI crossing types with respect to travel time and stopped delay, but the standard intersection had an equal or fewer number of stops. Future research includes incorporating pedestrian-bicycle safety, comfort, and the relative effects of these crossing alternatives on vehicular operations. Finally, a summary of the multimodal aspects of Reduced Crossings IU-Turn (RCUT) intersections, as studied by researchers at The Citadel is provided in Appendix B of this report. The reduction of the number of conflict points to as few as eight provided by RCUT intersection configurations was found to be beneficial to all roadway users including, motor vehicle traffic, pedestrians, bicyclists, and transit users.

Green, Lewis, et al. The Austroads Guide to Traffic Management consists of 13 Parts. It provides a comprehensive coverage of traffic management guidance for practitioners involved in traffic engineering, road design and road safety. Guide to Traffic Management Part 6: Intersections, Interchanges and Crossings Management is concerned with traffic management at all types of intersections where road users must join or cross another stream of traffic. It focuses on traffic management issues and treatments related to intersections, interchanges and crossings. It does not provide information on the geometric design of the treatment as this is provided in the Austroads Guide to Road Design Part 4, 4A, 4B and 4C. Guidance on the management of road sections which are not part of the intersection or interchange is provided in the Austroads Guide to Traffic Management Part 5: Link Management. Part 6 describes the appropriate use of, and design of, the various intersection types and the techniques that need to be applied if efficient and safe intersections are to be provided to the road user. All categories of road use – including cars, trucks, public transport, motorcycles, cyclists and pedestrians, including people who have disability or mobility difficulty, are addressed in the Guide

Brown, Edara, et al. NCHRP Synthesis. As traffic demand increases, the use of alternative intersections, such as roundabouts, diverging diamond interchanges, J-turns, median U-turns, and continuous flow intersections, is becoming more prevalent within the United States. An alternative intersection is an intersection where traffic movement is re-routed from a traditional intersection form to remove major conflict points. This synthesis report documents the evaluation and selection processes within state departments of transportation for intersection projects. Information for this study was gathered through a literature review, a survey of state departments of transportation, and follow-up interviews with selected agencies. Six case examples provide additional information on alternative intersection design and selection practices. A key finding of the synthesis was that DOTs use several different approaches and tools for the evaluation and selection of intersection types. Nine states have implemented Intersection Control Evaluation (ICE) policies that provide procedures for screening, analysis, selection, documentation, and approval of alternative intersections. DOTs have found ICE policies to be beneficial for standardizing procedures, documenting the decision-making process, and promoting the use of alternative intersections.

NACTO. This guide focuses on intersection design strategies to increase the visibility of cyclists, reduce motorized vehicle turning speeds, give priority to cyclists, and ultimately reduce vehicle-bike and vehicle-pedestrian conflicts. It is a companion publication to the National Association of City Transportation Officials' (NACTO's) Urban Bikeway Design Guide (2011). Strategies for protected intersections, dedicated intersections, minor street crossings, and signal phasing are described along with implementation guidance.

Woolley, Stokes, et al. This report provides a compendium of knowledge on Safe System treatments and identifies real world experience in the practical application of solutions that can mitigate crash severity.
The Safe System is internationally regarded as the best practice approach to road safety. Although Australia and New Zealand have been early adopters of the approach since 2004, there has generally been a lack of clarity amongst practitioners on how best to integrate the approach into their daily activities.
Assessment frameworks and tools are also now emerging that allow the alignment with Safe System be better quantified. A hierarchy of treatments is described that provide practitioners with a basic understanding of the types of practices that should now be applied on a trajectory towards a Safe System. Primary treatments are capable of virtually eliminating death and injury and certain supporting treatments can transform the network a step closer to reducing the overall harm being caused.

Gore, Hanshaw, Venter. The purpose of this project was to provide an intersection design and a structural bridge design for Louisiana State University to achieve the mobility goals of the LSU Master Plan. The team determined technical bridge and intersection design components and created three preliminary intersection and bridge designs. The final recommendation was to build a Warren Truss bridge and an intersection that encourages walking and biking with design features including a shared space for pedestrians and cyclists, bike crossings, and crosswalks.

Barrett, Murphy, et al, The intersection of Shawsheen Street, Patten Road, Foster Road, and Beech Street in Tewksbury, Massachusetts can no longer provide safe and efficient travel due to poor design and increasing traffic. Utilizing traffic engineering data collection and design, problems that affect safety and throughput were identified, and a design to alleviate those problems was created. By using Highway Capacity Software analysis, AutoCAD modeling, and professional intersection design, this design sought to improve the health and wellbeing of the people of Tewksbury. Includes information on ADA compliance.

Jurewicz, Sobhani, et al. Intersection crashes account for approximately 30% of severe injuries in Australia and New Zealand. This study sought to improve understanding of the key factors in intersection severe injury crashes, and to develop initiatives to improve the design of intersections for better alignment with the Safe System objective of minimising death and serious injury. The study reviewed recent literature and data to synthesise the following Safe System intersection design principles: minimise conflict points, remove/simplify road user decisions, minimise impact angles, and minimise entry and impact speeds. Using inputs from literature and data findings, a new safety analytical method, and practitioners, the study proposed nine innovative intersection design concepts seeking to increase Safe System alignment across a wide range of scenarios (urban/rural, new/retrofit). These design concepts form a starting point for
practitioners’ trials and refinement. The study concluded that achievement of Safe System for intersections requires significant supporting contributions from emerging transport disciplines such as C-ITS, autonomous vehicles, and Movement and Place.

Goodchild, McCormack, et al. This research report investigates the relationship between pedestrians and bicyclists on paths parallel to railroad tracks and with a road perpendicular to the path. The possible conflicts at intersections within these design parameters are of concern to ODOT, and therefore, has been recognized as an opportunity to conduct research that improves this type of intersection. The goal of this research project is to create a Guidebook that suggests appropriate path or road treatments for crossings, while also acknowledging and complimenting the unique site conditions present at the intersection. The report contains an extensive literature review, including existing railroad treatment options, and a description of the conducted field surveys and pedestrian, bicycle, vehicle, and train counts from the video. The report could help future work, such as developing more design solutions for paths parallel to tracks and the road perpendicular to the path. A preliminary guidebook is exemplified in the conducted case studies. It is intended to be a user friendly tool for city planners and engineers to assess a crossing and identify appropriate treatment options to improve the path and road user environment, and overall safety for all users

Shokrolah Shirazi, Morris. Intersections are known for their integral and complex nature due to a variety of the participants behaviors and interactions. This article presents a review of recent studies on behavior at intersections and safety analysis for three types of participants at intersections: vehicles, drivers, and pedestrians. The paper emphasize on techniques which are strong candidates for automation with visual sensing technology. A new behavior and safety classification is presented based on key features used for intersection design, planning, and safety. In addition, performance metrics are introduced to evaluate different studies and insights are provided regarding the state of the art, inputs, algorithms, challenges, and shortcomings.

Easa. No design guidelines are available for pedestrian crossing sight distance (PCSD) and associated lateral clearance on roadways. Guidelines are available only for intersection (vehicle) sight distance (ISD) at two-way stop-controlled (TWSC) intersections. This paper presents a new model for pedestrian crossing time that is used to establish a general model for lateral clearance at crossings located on curved (or straight) roadways. The model is applicable to all crossing types: TWSC intersections, midblocks, and freeway ramps. The model can be used to determine the maximum lateral clearance to the right or to the left of the crossing or the required lateral clearance at a specified location. The distance from
the crossing within which on-street parking should be restricted to
satisfy PCSD is also determined. A single spreadsheet that is applicable to all crossing types was developed. A comparison with ISD shows that lateral clearance needs for pedestrians are not satisfied by those currently available for vehicles. Design aids for all crossing types are presented. The method presented in this paper promotes pedestrian safety and should be of interest to the highway community.

Suderman, Redmand, Cantor. The City of Winnipeg has one of the highest modes shares of pedestrians in the prairies (Statistics Canada, 2011 National Household Survey), and continually investigates new methods for improving the safety of pedestrians at signalized intersections through geometric design improvements. Our design approach is typically through the lens of people with a range of disabilities but the end result is increased safety for people of all ages and abilities. This also results in making the pedestrian environment more convenient which encourages people to walk more. The changes in geometric design of the intersection must also be done in unison with the placement and utilization of the evolving traffic control devices.

Meade, Zegeer, Bushell. This document represents an effort to compile all known research on the effect of the pedestrian safety countermeasures discussed in PEDSAFE: Pedestrian Safety Guide and Countermeasure Selection System. It is intended to serve as a companion document for the guide, providing a complementary overview of the researchers, research methods, and evaluation results that have guided the development and design of pedestrian safety countermeasure

LaPlante, Van Houten, et al. Reducing crashes involving pedestrians and bicyclists continues to be a major concern in the design of Michigan roads. In seeking to improve the safety of pedestrians, bicyclists, and motorists on Michigan roads, it is important to balance the needs of improved safety and mobility. This report provides a comprehensive review of safety improvements through a series of reports: A pedestrian and bicycle crash analysis in Michigan; a review of national design guidelines with respect to pedestrian and bicycle improvements; a case study analysis of recently completed improvements in Michigan; an analysis of existing guides and manuals that influence the design of roadways in Michigan; finally, and a set of recommended best design practices for walking and bicycling in Michigan

Stamatiadis, Kirk, et al. The purpose of this report is to document the development of the Intersection Design Alternative Tool (IDAT) developed for the Kentucky Transportation Cabinet. IDAT provides an automated objective design and evaluation approach of 14 alternative intersection designs to assist in the conceptual design of at-grade intersections. The tool evaluates intersection operations, safety performance, bicycle/pedestrian accommodation and has the ability to assist access management implementation.

Hughes, Jagannathan, et al. Today’s transportation professionals are challenged to meet the mobility needs of an increasing population with limited resources. At many highway junctions, congestion continues to worsen. Drivers, pedestrians, and bicyclists experience longer delays and greater exposure to risk. Today’s traffic and safety problems are more complex and complicated. Conventional intersection/ interchange designs are sometimes found to be insufficient to mitigate transportation problems. Consequently, many engineers are investigating and implementing innovative treatments in an attempt to think outside the box. This report covers four intersection designs and two interchange designs that may offer additional benefits compared to conventional at-grade intersections and grade-separated diamond interchanges. The six alternative treatments covered in this report are displaced left-turn (DLT) intersections, restricted crossing U-turn (RCUT) intersections, median U-turn (MUT) intersections, quadrant roadway (QR) intersections, double crossover diamond (DCD) interchanges, and DLT interchanges. The information presented in this report provides knowledge of each of the six alternative treatments including salient geometric design features, operational and safety issues, access management issues, costs, and construction sequencing and applicability.

Caltrans. Improving both safety and mobility at intersections for pedestrians and bicyclists presents a significant technical challenge for planners, engineers and other highway designers due to the complexity of the road environment and the number of tradeoffs to consider. This
Guide is intended to help meet that challenge by presenting common issues faced by pedestrians and bicyclists at intersections and interchanges and best practices for addressing them through design and operational changes.

Fitzpatrick, Wooldridge, Blaschke. Intersections are an important part of a highway facility because the efficiency, safety, speed, cost of operation, and capacity of the facility depend on their design to a great extent. Each intersection involves through- or cross-traffic movements on one or more of the highways and may involve turning movements between these highways. Such movements may be facilitated by various geometric designs and traffic controls, depending on the type of intersection. The main objective of intersection design is to facilitate the
convenience, comfort, and safety of people traversing the intersection while enhancing the efficient movement of motor vehicles, buses, trucks, bicycles, and pedestrians. In order to design intersections that are both functional and effective, designers need current information regarding intersection design that is
easily accessible and in a user-friendly format. The prime objective of the Texas Department of Transportation Project 0-4365 is to produce this reference document, the Urban Intersection Design Guide,
to provide this information.

Chan. The overall IDS research plan was constructed to realize, in slightly more than three years, the requirements, tradeoffs assessment, and technology investigations necessary to define an IDS. Toward the end of the project we will combine our understanding of the problem definition, IDS technologies and our integration experience with a standard Caltrans intersection (with advanced controller) and design a deployable IDS demonstration that can be field tested.

Noyce, et al. The purposes of this report are to (1) demonstrate practical design measures and tools that will improve intersection safety and operations for all users of the roadway, (2) provide examples of effective applications and (3) discuss experiences with innovative solutions. Many of these measures, tools, applications and innovative solutions were presented and discussed during the ITE 2004 Technical Conference and Exhibit, “Intersection Safety: Achieving Solutions Through Partnerships.” Report includes:
• Chapter 4, Pedestrian and Bicyclist Safety at Intersections
• Chapter 5, Geometric Design