I am modeling a corridor with eight 4 leg and one RCUT intersection. the corridor is coded in VISSIM. I used the SSAM, but does it work for RCUT intersections too? The values I get are not very convencing, Is there any other way to measure safety from VISSIM output?
You might try to compare SSAM conflict point estimates (only a surrogate safety measure) to Highway Safety Manual (HSM) crash estimates (a more explicit safety measure). I am not an HSM expert, but a recent conference presentation from Gilbert Chlewicki (Advanced Transportation Solutions) showed that Professors Edara (University of Missouri) and Hummer (Wayne State University) developed crash modification factors of approximately 0.536 for RCUT intersections. This means RCUTs have far fewer crashes than conventional intersections. Chlewicki, who specializes in alternative intersection design and operation, explained that RCUT intersections produce fewer crashes because they have fewer conflict points than conventional intersections.
Access Management CMFs are limited in the CMF clearinghouse. We worked on a project in Louisiana where we evaluated the safety performance of two alternatives, RCUT vs continuous green T-intersections. We used the HSM predictive methods to obtain the safety performance of the corridor under no build conditions, and then applied various CMFs to account for the operational changes/features of each of the proposed intersections. Results of the analysis indicated that the RCUT intersection reduced left turn crashes by 44%.
Thanks David and Dante for your help. To use the HSM predictive medthods, do I need the crash data? As i am working with no build situation, I am afraid I do not have the crash data. Can you please post me a link?
Although I do not have experience with using HSM methods, I believe someone once said they could be applied with or without historical crash data. For example, using the HSM without crash data might be similar to using the Highway Capacity Manual (HCM) with estimated saturation flow rates, instead of measured saturation flow rates. In other words, results might be somewhat less reliable.
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