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DOI: 10.7708/ijtte.2016.6(1).04

6 / 1 / 38-50 Pages


Tahmina Khan - Civil and Environmental Engineering Department, University of Alabama in Huntsville, Alabama, United States -

Michael Anderson - Civil and Environmental Engineering Department, University of Alabama in Huntsville, Alabama, United States -


A diverging diamond interchange (DDI), a freeway and arterial interchange design, uses crossovers at the ramp intersections to eliminate conflicts between arterial through traffic and the left turning traffic from both the arterial and the ramps. The conventional diamond interchange (CDI) compared with the DDI has similar on-ramps and off-ramps, but there is a change in the number of lanes on the arterial. A case study has been conducted for an interchange in Athens, Alabama. The existing interchange is a conventional diamond interchange which is compared with a DDI built at the same location by using Synchro/Simtraffic as a simulation tool. The analysis focused on determining level of service and vehicle delay for the two interchange types. In this project effort was made to know if a DDI is the right solution for all interchange locations through the examination of a single location and adjustments to traffic volumes under numerous combination of turning movement scenarios where variation of capacity and the influence of proximity of adjacent intersections were also included. Finally, it was concluded that DDI cannot be an appropriate measure to improve the current CDI network for the study area since only 4 special cases it performs better than CDI. And DDI cannot be the effective traffic calming measure if it is associated with upstream or downstream intersections.

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The authors would like to acknowledge the support of Alabama Department of Transportation for the funding to conduct the research leading to this article.


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