Evaluating the Economic and Safety Trade-offs of Interchange and Access Drive Separation Distances

The research project will evaluate whether the Iowa Department of Transportation’s (Iowa DOT) minimum separation standards between interchanges and first access points are overly restrictive and potentially detrimental to development opportunities around those interchanges. To achieve this, the project will utilize deep learning techniques to analyze high-resolution aerial photographs to identify interchanges on state-owned roadways, their first driveway access points, and the specific aspects of development status, such as the presence of commercial or residential buildings, vacant land, or agricultural use of the surrounding land. Crash data from the Iowa dataset will be examined to assess safety outcomes about these separation distances. A critical part of the analysis will involve evaluating the economic potential of these lands and estimating the impact of separation standards on land utilization and potential economic growth. In addition to state-owned interchanges, the study will identify non-interchange intersections with roadways with similar AADT levels, the number of lanes, if a median is present, and other relevant geometric features to access management. The closest access point will be determined for these intersections, mirroring the approach taken with the interchanges. The crash history for these locations will be retrieved to compare the safety performance of interchanges and non-interchange intersections directly. This analysis, focusing on interchange and access point separation distances, will help isolate the effect of these separation standards on safety and development, controlling for traffic volume and other features. By examining interchange and non-interchange sites under similar conditions, the research will determine if the minimum separation distances at interchanges are justified or could be adjusted to better balance safety with economic development, potentially informing future policy decisions. The research will also determine the amount of developable land that could be available should the standards be relaxed.

Language

• English

Project

• Status: Active
• Funding: $164,950.26
• Contract Numbers:

  69A3552348307

• Sponsor Organizations:

  Office of the Assistant Secretary for Research and Technology

  University Transportation Centers Program
  Department of Transportation
  Washington, DC  United States  20590
• Managing Organizations:

  Mid-America Transportation Center

  University of Nebraska-Lincoln
  2200 Vine Street, PO Box 830851
  Lincoln, NE  United States  68583-0851
• Project Managers:

  Stearns, Amy

• Performing Organizations:

  University of Iowa, Iowa City

  National Advanced Driving Simulator, 2401 Oakdale Blvd
  Iowa City, IA  United States  52242-5003
• Principal Investigators:

  Hanley, Paul

• Start Date: 20240601
• Expected Completion Date: 20260630
• Actual Completion Date: 0
• USDOT Program: University Transportation Centers Program

Subject/Index Terms

• TRT Terms: Crash data; Deep learning; Economic development; Highway design; Highway safety; Image analysis; Interchanges and intersections; Land use planning; Traffic incidents
• Identifier Terms: Iowa Department of Transportation
• Geographic Terms: Iowa
• Subject Areas: Data and Information Technology; Economics; Highways; Safety and Human Factors;

Filing Info

• Accession Number: 01971746
• Record Type: Research project
• Source Agency: Mid-America Transportation Center
• Contract Numbers: 69A3552348307
• Files: UTC, RIP
• Created Date: Nov 19 2025 2:36PM