Benefit-Cost Analysis of Roundabouts to Support Long Range Investment Policy

Despite significant investments and successful use of roundabouts throughout the state, Oregon currently lacks clear evaluation of the benefits and costs of roundabouts tailored to the state’s needs. The states of New York and Virginia have adopted a “roundabout first” policy, identifying roundabouts as the preferred design for intersections where feasible because of benefits to lifecycle system cost, safety, and traffic flow with greenhouse gas emission reduction benefits. However, Oregon lacks a systematic evaluation including equity concerns to support policy development. Traffic signals on the state highway system are crucial to the safety, operation, and management of the Oregon highway system. Oregon has 1,480 traffic signals, 84% are owned by the Oregon Department of Transportation (ODOT). A large proportion are nearing the end of their life. Some signals are aging faster due to environmental issues, such as coastal salt air and weather. Signal operations are key to addressing safety, impacting autos, trucks, bikes and peds. As connected and autonomous vehicles (CAVs) are introduced into the Oregon fleet, ODOT will be working to develop communication capabilities between CAVs and signals, which will require expanded investment over time and increasing maintenance. As ODOT implements more roundabouts (RABs) on the state system, they are seeing improvements in traffic performance, improved safety, and reduced maintenance costs over time. Other agencies across the United States are beginning to see evidence of reduced cost of long-range maintenance. This begs the question whether ODOT should establish a policy to move away from investing in signal replacement and establish a long-term strategy implementing roundabouts based on comprehensive lifecycle costs and benefits. Lifecycle costs of intersection management vary by design. In general, signals are less expensive to put into place initially, require ongoing maintenance and replacement costs, and include severe-injuries to property-damage-only crash costs. Roundabouts cost more to put into place initially, require relatively low maintenance costs and involve fewer crashes and reduced severity. ODOT’s forecast budget falls far short of meeting investment needs, especially for maintenance and preservation. This means more than ever ODOT must be strategic in making investment decisions and consider comprehensive lifecycle costs when choosing projects that provide the best return on investment for the state transportation system. Reducing lifecycle costs would help ODOT make progress toward good stewardship of public resources.

Language

• English

Project

• Status: Active
• Sponsor Organizations:

  Federal Highway Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Managing Organizations:

  Oregon Department of Transportation

  355 Capital St NE MS42
  Salem, Oregon  United States  97301
• Project Managers:

  Bagwell, Matt

• Performing Organizations:

  Portland State University

  P.O. Box 751
  Portland, OR  United States  97207-0751
• Principal Investigators:

  Anderson, Jason

• Start Date: 20241001
• Expected Completion Date: 20260930
• Actual Completion Date: 0

Subject/Index Terms

• TRT Terms: Benefit cost analysis; Intersections; Roundabouts; Strategic planning
• Geographic Terms: Oregon
• Subject Areas: Design; Economics; Highways; Operations and Traffic Management; Planning and Forecasting;

Filing Info

• Accession Number: 01964200
• Record Type: Research project
• Source Agency: Oregon Department of Transportation
• Files: RIP, STATEDOT
• Created Date: Aug 28 2025 4:17PM