Navigating Safety at Unsignalized Intersections
From 2010 to 2012, more than 70 percent of all intersection-related fatal crashes nationwide occurred at unsignalized intersections. Unsignalized intersections are those at-grade junctions of two or more public roads where the control of right-of-way is determined by the presence of a YIELD or STOP sign, or no sign at all (uncontrolled). The majority of these intersections are owned and operated by local agencies, many of which do not have professional traffic safety engineers on staff. The Unsignalized Intersection Improvement Guide (UIIG) provides practical guidance to assist these agencies with making decisions on safety treatments.
The guide, prepared under the National Cooperative Highway Research Program and cofunded by the Federal Highway Administration, is designed to aid local agency practitioners in selecting treatments (design, operational, maintenance, enforcement) to improve the safety, mobility, and accessibility of all users at unsignalized intersections. It can help confirm the presence of a problem, identify contributing factors, and point to possible countermeasures.
The guide is a Web-based resource so that it can be modified easily to incorporate the most up-to-date information for users. Through an FHWA task order, the Institute of Transportation Engineers (ITE) hosts the Web-based content at www.ite.org/uiig.
What’s on the Web Site
The site is presented in two main parts: Information and Toolkit.
The Information component contains sections on the types of unsignalized intersections, typical problems, a five-step improvement process, and treatments. This section provides access to factsheets on 75 treatments. Each factsheet includes a brief explanation of the treatment, the problems it addresses, the target crash types, the applicable intersection characteristics and conditions, key points related to treatment selection and implementation, a list of guidance documents, and links to the Crash Modification Factors Clearinghouse and imagery from intersections at which the treatment has been deployed.
Also included in the Information area of the site are a summary of what the Manual on Uniform Traffic Control Devices says about the various traffic control devices, the Americans with Disabilities Act and pedestrian considerations, and guidance on maintenance activities.
The Toolkit is the operative portion of the site. It contains three tools to provide practitioners with applications and examples related to assessing and improving unsignalized intersections. The UIIG Treatment Selection Tool enables users to access the 75 factsheets by conducting a keyword search, by viewing a complete listing of all the treatments, or by selecting a perceived problem and treatment type. Users also can generate a more focused listing of treatment alternatives by answering any or all of six questions to provide information on the subject intersection’s basic characteristics. Based on these responses, users are then presented with factsheets on potential treatments.
The second tool, the UIIG Intersection Assessment and Inventory Form, guides agencies in compiling and analyzing information related to the physical and operational characteristics of an unsignalized intersection. The form is a downloadable Microsoft® Excel® spreadsheet. Agencies also can use it to build a simple database of their unsignalized intersections.
The third tool is the UIIG Citizen Traffic Service Request Form, which agencies can use to invite the public to notify them about potential problems.
User Feedback and Updates
Users can report problems, suggest changes to technical content, share experiences in deploying the various treatments, and submit photographs of intersection problems or treatments directly through the Web site, via email, or through U.S. mail.
Under the FHWA task order, ITE has assigned staff to maintain the site and content for 2 years. A technical committee consisting of the ITE council members and at least one FHWA representative will help keep the content updated and relevant.
“The goal is to provide a rich and accessible resource, especially for staff of smaller local agencies,” says Jeff Shaw, the intersection safety program manager in FHWA’s Office of Safety. “The input from the ITE community over the 2-year period will help keep the content relevant to all audiences.”
Hugh W. McGee, P.E., is a consultant to VHB and the principal investigator for the UIIG project.
Jonathan Soika, P.E., is a senior transportation engineer with VHB and a coauthor of the UIIG.