Safety analysis of the new synchronized and milwaukee B interchanges in comparison to existing designs. (December 2017)

• Record Type: Journal Article
• Authors: Molan, Amirarsalan Mehrara; Hummer, Joseph E.
• Is Part Of: Accident analysis and prevention. Volume 109(2017)
• Page Start: 29
• Page End: 35
• Publication Date: 2017-12
• Subjects: Highway safety -- Alternative interchanges -- Conflict point -- SSAM -- Simulation; Accidents -- Prevention -- Periodicals; Accident Prevention -- Periodicals; Accidents -- Prévention -- Périodiques; 363.106
• DOI: 10.1016/j.aap.2017.09.026
• Languages: English
• ISSNs: 0001-4575

Abstract

Highlights: Safety performance of two proposed service interchange designs were reviewed. The DDI and the new Milwaukee B were introduced as the safest interchange in terms of conflict frequency. The new synchronized had the best performance from the viewpoint of severity of the conflicts. Synchronized and DDI can be considered as the safe alternatives for failing diamond interchanges. Abstract: Interchanges have high crash rates and large impacts on traffic operations. The main objective of this research is to analyze the safety performance of two new interchanges, the synchronized interchange and the Milwaukee B interchange. The primary method of study was microscopic simulation modeling using the Surrogate Safety Assessment Model (SSAM) program to estimate the quantity and type of conflicting interactions in each interchange. A comprehensive series of simulation scenarios were considered to include different conditions of traffic volumes, traffic turning ratios, traffic distribution, and heavy vehicles percentages. Afterward, outcomes were analyzed with two-way Analyses of Variance (ANOVAs) to compare the mean values of conflicts. Based on the results, the diverging diamond interchange (DDI) and Milwaukee B were the safest designs regarding observed conflicting interactions in the simulation models; however, the DDI did not seem as reliable from the viewpoint of wrong way movements. The new synchronized interchange, the parclo B, and the Milwaukee A (an existing interchange in Milwaukee, WI) showed the same rate of conflicts. The synchronized interchange may be advantageous because it was estimated to reduce the severity of crashes due to fewer crossing conflicts, a lower speed of conflicts, and a higher time to collision. The conventional diamond was the most dangerous design based on our measures. The DDI and the synchronized interchange look like plausible substitutes for reconstructing an unsafe diamond interchange due to the similarities in their required space.