U of MNUniversity of Minnesota
Center for Transportation Studies

Programs & Labs

Rural Unsignalized Intersections

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Overview: A national problem

Intersections account for more than two million crashes in the United States every year. In rural areas, crashes are often more severe than in urban areas because of higher vehicle speeds and longer emergency response times. Over 60 percent of all intersection-related fatal crashes in Minnesota between 1998 and 2000 occurred at rural through-stop intersections—typically, where a high-speed, high-volume rural highway crosses a low-volume feeder road.

The American Association of State Highway and Transportation Officials (AASHTO) and the Transportation Research Board (TRB) have recognized the severity of this problem. The AASHTO Strategic Highway Safety Plan specifically addresses the need for new technologies to improve highway intersection safety.

Installing traffic signals has been the most common response to high crash rates at rural unsignalized intersections. However, traffic signals often fail to reduce the total number of crashes, as rear-end collisions increase. Signals also disrupt the flow of traffic, leading to delays and more crashes as fast-moving vehicles encounter vehicles that have been slowed down by a red signal.

The ITS Institute's rural intersection collision avoidance research takes a different approach: helping drivers make better decisions, instead of regulating and disrupting the flow of traffic. This approach combines the Institute's expertise in traffic monitoring, data processing and computation, and human factors engineering to improve safety.

ITS Institute research projects

The ITS Institute is involved in a set of interrelated research projects focused on reducing crashes at rural intersections:

Cooperative Intersection Collision Avoidance Systems—Stop Sign Assist (CICAS-SSA)

The ITS Institute is currently part of the United States Department of Transportation's national research effort to reduce intersection crashes. Our research focuses on an infrastructure-based driver-assistive system to help prevent collisions at rural highway intersections without disrupting traffic flow. Building on earlier research, this project will culminate in a Field Operational Test of the driver-assistive system in Minnesota.

Learn more about CICAS-SSA:

Reducing Crashes at Rural Intersections: Toward a Multi-state Consensus on Intersection Decision Support

The ITS Institute and the Minnesota Department of Transportation initiated this national pooled-fund study aimed at developing a widely deployable framework for Intersection Decision Support. Working with seven partner states, the ITS Institute developed the Minnesota Mobile Intersection Surveillance System, a portable sensor suite that gathered data in a variety of conditions across the country.

Learn more about the multi-state pooled fund research:

The Infrastructure Consortium: Intersection Decision Support

With support from the Federal Highway Administration, the ITS Institute developed the Rural Intersection Decision Support concept to address the problem of crashes at unsignalized rural highway intersections. The approach pioneered in this research was developed in later projects.

Learn more about the Infrastructure Consortium research: