01663966

Component

Two-way stop-controlled (TWSC) intersections on four-lane rural highways rarely experience problems with congestion, but can be prone to higher than acceptable crash rates. In particular, crashes from entering left turn vehicles are among the most frequent, and have the most severe outcomes. Low-cost mitigations can reduce risk at these sites, but in extreme cases the facility can be reconstructed as a grade-separated interchange (GSI). While this is an effective solution in terms of safety, it is over-engineered and extremely costly for the demand volumes present. The restricted-crossing u-turn (RCUT) intersection design presents a cost-effective solution to mitigate safety concerns at TWSC intersections on rural highways. This study assesses the operational and safety expectations of TWSC, GSI, and RCUT facilities for different major road to minor road volume proportions. Case study sites were selected from among intersections currently being evaluated by the Nebraska Department of Transportation (NDOT) as potential GSI locations to resolve safety concerns. The base condition for traffic demand volume scenarios came from field data collection at a selected site in Palmyra, Nebraska. Results from VISSIM showed the GSI had the best operational performance, followed by the RCUT, and lastly the TWSC for all scenarios tested. Safety assessments using the Interactive Highway Safety Design Model predict that the RCUT intersection would greatly reduce crashes compared to the TWSC intersection, with better results than the GSI for some of the scenarios examined. Consequently, a cost-benefit analysis found the RCUT design to be the most cost-effective solution, recuperating construction costs within two years, with a 15-year return on investment for GSIs.

This paper was sponsored by TRB committee AHB65 Standing Committee on Operational Effects of Geometrics. Alternate title: Evaluation of Restricted-Crossing U-Turn Design as an Alternative to Grade-Separated Interchanges on Rural Highways

18-05639

English

18p

2018

Transportation Research Board 97th Annual Meeting

Digital/other

Figures; Photos; References; Tables

Benefit cost analysis; Case studies; Cost effectiveness; Crash rates; Four lane highways; Grade separations; Highway safety; Interchanges; Left turns; Rural highways; Traffic volume; U turns; Unsignalized intersections

Interactive Highway Safety Design Model; Nebraska Department of Transportation; VISSIM (Computer model)

Two way stop controlled intersections

Palmyra (Nebraska)

Economics; Highways; Operations and Traffic Management; Planning and Forecasting; Safety and Human Factors

Transportation Research Board Annual Meeting 2018 Paper #18-05639

TRIS, TRB, ATRI

Jan 8 2018 11:26AM