INTERCHANGE VS. AT-GRADE INTERSECTION ON RURAL EXPRESSWAYS. FINAL REPORT

This research compared the economic benefits and costs of replacing a two-way STOP-controlled intersection with either a signalized intersection or a full diamond interchange with STOP-controlled off-ramps. Road user benefits are based on the difference in road user costs among alternatives converted to present dollar values. The road user costs are comprised of five components: stopped delay, idle fuel, acceleration-deceleration delay, speed change running costs, and accident costs. A particular focus of this research was on the development of accident prediction models applicable to intersections and interchanges on rural expressways. Examination of the expected accident frequency for each jucition type indicates that a two-way STOP-controlled intersection is likely to have more accidents per year than a signalized intersection or an interchange under the same traffic demand conditions. Three scenarios were considered for the benefit-cost analysis of the two-way STOP-controlled intersection and the interchange. One scenario assumes four approach legs and a two-lane minor road cross section. A second scenario assumes four approach legs and a four-lane minor road cross section. A third scenario assumes three approach legs and a two-lane minor road cross section. The results of the benefit-cost analysis of the first scenario indicate that base year minor road demands of less than 2,000 vpd generally yield benefit-cost (B/C) ratios less than 1.0, indicating that an interchange is probably not economically justified. In contrast, minor road demands of more than 4,000 vpd generally yield B/C ratios greater than 2.0, indicating that an interchange is probably justified. Similar minor road demand thresholds are identified for the four-lane minor road scenario and the three-leg scenario. Minor road demand thresholds are slightly higher for these combinations, indicating the need for greater user benefits to justify the cost of constructing the interchange.

  • Corporate Authors:

    University of Nebraska, Omaha

    Department of Civil Engineering, 6001 Dodge Street
    Omaha, NE  United States  68182-0178

    Nebraska Department of Roads

    1500 Highway 2, P.O. Box 94759
    Lincoln, NE  United States  68509
  • Authors:
    • Bonneson, J A
    • McCoy, P T
  • Publication Date: 1992-5

Language

  • English

Media Info

  • Features: Figures; References; Tables;
  • Pagination: 50 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00624945
  • Record Type: Publication
  • Report/Paper Numbers: TRP-02-25-91
  • Files: TRIS, STATEDOT
  • Created Date: Sep 17 1993 12:00AM