Evaluating Safety Performance of the Offset Diamond Interchange Design using VISSIM and Surrogate Safety Assessment Model

Many of existing interchanges, which were built mostly in 1950s and 1960s based on old design guidelines, have operational and/or safety problems due to the inconsistency with current traffic and pedestrian demands. Therefore, upgrading existing designs based on recent policies and demands could result in improving the performance of old interchanges. This research evaluates traffic safety and pedestrian performance of the new offset diamond interchange (ODI) as a substitute for failing conventional interchanges. The ODI design, which showed potential in improving traffic operation in a past study by the authors, were compared to nine interchange designs using VISSIM and the Surrogate Safety Assessment Model (SSAM) in this study to examine the safety and pedestrian performance. Overall, 324 simulation scenarios were tested with various conditions of traffic and pedestrian volumes, turning traffic ratios, traffic distribution, and truck percentages. According to the results, the ODI showed potential to be a promising design in terms of safety and pedestrian performance. However, the diverging diamond interchange (DDI) resulted in fewer simulated conflicts compared to the new ODI. On the other hand, the ODI design had a better performance in terms of pedestrian performance.


  • English

Media Info

  • Media Type: Web
  • Features: Figures; References; Tables;
  • Pagination: 20p

Subject/Index Terms

Filing Info

  • Accession Number: 01763561
  • Record Type: Publication
  • Report/Paper Numbers: TRBAM-21-00515
  • Files: TRIS, TRB, ATRI
  • Created Date: Dec 23 2020 11:06AM