Intersections with dilemma zone protection can improve safety by more than 20 percent with only a two percent reduction in efficiency.

Exploring traffic signal control strategies in a connected vehicle environment.


Summary Information

This study presented research on how dilemma zone protection can be implemented at intersections that use connected vehicle data. Dilemma zone protection was presented as a safety aspect of signal operations that could be improved. The dilemma zone was defined as a section of roadway at an intersection where a driver can not stop safely or clear the intersection safely at the onset of the yellow change interval. Rather than eliminating the dilemma zone, which could have large negative impacts on corridor efficiency, researchers examined ways to reduce the number of vehicles in the dilemma zone (NVDZ) while maintaining acceptable loss of efficiency.


In order to balance safety and mobility, a multi-objective optimization model was used in combination with an economic model to calculate the minimum combined cost of the two objectives (i.e., minimize delay and minimize NVDZ) using a transportation network simulator (VISSIM). Researchers examined safety and mobility with and without dilemma zone protection.

  • The outcome from balanced objectives show that by sacrificing 2 percent efficiency which increases delay, safety can be improved by 20 percent which lowers overall cost. The difference was caused by extending green time by one second on the mainline.
  • The green extension reduced the NVDZ by 23.79 percent on the mainline and increased delay by 1.56 percent on the side streets.

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Intelligent Traffic Control in a Connected Vehicle Environment

Author: Feng, Yiheng

Published By: University of Arizona

Dissertation for Industrial Engineering PhD

Source Date: 6/15/2015



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Goal Areas


Typical Deployment Locations

Metropolitan Areas, Rural Areas


traffic signals, adaptive signals

Benefit ID: 2015-01007