Assessment of Safety and Operation Performances of CFIs and DDIs in Utah

Details

• Creators:
  Dhimal, Ramesh ; Neupane, Kiran ; Song, Yu (Fred) ; Zlatkovic, Milan
• Corporate Creators:
  Center for Transformative Infrastructure Preservation and Sustainability (CTIPS) Region 8 University Transportation Center (UTC) ; North Dakota State University
• Corporate Contributors:
  United States. Department of Transportation. University Transportation Centers (UTC) Program ; United States. Department of Transportation. Office of the Assistant Secretary for Research and Technology
• Subject/TRT Terms:
  Bayes' Theorem Calibration Continuous Flow Intersection Diamond Interchanges Diverging Diamond Interchange Empirical Methods Evaluation And Assessment Extreme Value Theory Performance Surrogate Safety Measures
• Publication/ Report Number:
  CTIPS-26-004
• Resource Type:
  Tech Report
• Geographical Coverage:
  United States ; Utah
• Corporate Publisher:
  Center for Transformative Infrastructure Preservation and Sustainability (CTIPS) Region 8 University Transportation Center (UTC)
• Abstract:
  The Diverging Diamond Interchange (DDI) and the Continuous Flow Intersection (CFI) represent significant innovations in roadway design, offering superior operational performance and enhanced safety compared to conventional signalized ramp terminals and intersections. This study conducts a comprehensive evaluation of these two designs, focusing on both traffic flow and safety outcomes. The research begins by establishing a safety integrated calibration and validation framework for microscopic traffic simulation models using PTV VISSIM. Unlike traditional approaches, this framework incorporates surrogate safety analysis by embedding bivariate Peak Over Threshold (POT) modeling from Extreme Value Theory (EVT) to jointly capture conflict severity using Time to Collision (TTC) and Maximum Deceleration (MaxD). This dual-purpose modeling approach allows for the estimation of crash frequency directly from simulated conflicts while maintaining operational fidelity. The calibration achieved high accuracy, with GEH values below 5 for all movements and minimal speed errors, and simulation-based crash estimates for CFIs differed from observed frequencies by only 0.07 crashes per year. Validation using 2019 data further confirmed the predictive capability and generalizability of the models.
• Format:
  PDF
• Funding:
  69A3552348308
• Collection(s):
  University Transportation Centers
• Main Document Checksum:
  urn:sha-512:407d0ac8d7bfdbb763d07b1fb3eb28eb11f51197fdb9edf9659d5dcac85be617f35a0e28832dd473b99fb8099c67b9d5a6a8329eed15385ce0e0a98b4238bba3
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/92899/dot_92899_DS1.pdf
• File Type:
  [PDF - 6.57 MB ]