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Unsignalized Intersection Improvement Guide - Practical guidance for improving the safety, mobility, and accessibility at unsignalized intersections.

Why the UIIG

From 2010 to 2012, there were nearly 21,000 fatal crashes occurring at or related to intersections across the United States. Of those, more than 15,000—more than 70 percent—occurred at intersections that are not under the control of a traffic signal.1 The majority of these unsignalized intersections are owned and operated by local agencies, many of which do not have professional traffic engineers on staff. This Unsignalized Intersection Improvement Guide (UIIG) has been developed to assist practitioners at such agencies in selecting design, operational, maintenance, enforcement, and other types of treatments to improve safety, mobility, and accessibility at unsignalized intersections. Originally produced under Project No. 03-104 of the National Cooperative Highway Research Program, the web-based UIIG is now hosted by the Institute of Transportation Engineers (ITE) under the sponsorship of the Federal Highway Administration (FHWA) Office of Safety.

7 of every 10 fatal intersection crashes in the U.S. from 2010 to 2012 occurred at unsignalized intersections.

Using the UIIG

The purpose of the UIIG is to assist and guide users through the process of evaluating their unsignalized intersections and identifying opportunities to enhance their safety and operational performance. The contents of the UIIG are presented under two sections—Information and Toolkit. The Information section provides important background material related to the types, users, common problems and treatments, and general considerations associated with unsignalized intersections.  The Toolkit provides a number of resources to assist the user in (1) collecting data on the existing conditions and characteristics of the intersection and (2) identifying potential treatments that may improve the safety and mobility at the intersection. These tools include a sample citizen input form, a Microsoft Excel-based unsignalized intersection assessment and inventory form, and an unsignalized intersection treatment selection tool.

It is recommended that first-time users of the UIIG review the material in the Information section to familiarize themselves with basic principles and issues concerning unsignalized intersections. Special attention should be given to the Improvement Process, which outlines a series of steps for identifying and addressing problem locations. The Treatment Selection Tool can then be used to identify alternative treatments that may address these problem locations individually or systemically across a jurisdiction. The UIIG contains hyperlinks to many external resources that can provide a wealth of information related to the safety, mobility, and accessibility at unsignalized intersections. Users are advised that they should review these resources (and others that become available) and consult the expertise of a licensed Professional Engineer when considering any substantive changes to their transportation network.

Questions and Feedback

Questions and feedback related to the UIIG contents and functionality are welcomed and can be submitted by clicking on the tab at the lower right-hand corner of any UIIG webpage. It is envisioned that the UIIG will be updated annually, and all user feedback will be considered during each update.

1. Query of Fatality Analysis Reporting System (FARS) Web-Based Encyclopedia, National Highway Traffic Safety Administration, accessed on December 4, 2014.