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Mid-America Transportation Center

Dilemma Zone Protection on High-Speed Arterials

Final Report
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Researchers

  • Principal Investigator: Justice Appiah (jappiah2@unl.edu (402)472-1975)
  • Project Status
    Complete
    About this Project
    Brief Project Description & Background
    Driver behavior within the dilemma zone can be a major safety concern at high-speed signalized intersections, especially for heavy trucks. The NDOR was one of the first state transportation agencies to implement advance detection systems for dilemma zone protection on its isolated intersections. These systems provide information (via flashing signal heads and a warning sign) to drivers regarding whether they should be prepared to stop as they approach a traffic signal. The decision on whether to provide information to the drivers is a function of a number of parameters including the presence of vehicles on the roadway (identified via an upstream detector), the phase sequence, and where in the cycle the current signal timing plan is operating. A number of states have adopted similar systems; however, the operating algorithm is unique to Nebraska. The benefits of the NDOR system at improving intersection safety at isolated signalized intersections operating in the fully-actuated mode have been documented. However, the system is yet to be deployed at closely-spaced high-speed signalized intersections operating in the coordinated mode.
    Research Objective
    The objective of this research is to study the potential benefits of deploying the NDOR actuated advance warning system on high-speed arterials operating in the coordinated mode, and to develop guidelines for implementation.
    Potential Benefits
    The end results of the study will be a set of guidelines, based on empirical results from Nebraska, which can be used to: (i) identify candidate locations for installing the actuated advance warning system; and (ii) select appropriate design parameter values to realize the full benefits of the system.
    Abstract
    Driver behavior within the dilemma zone can be a major safety concern at high-speed signalized intersections, especially for heavy trucks. The Nebraska Department of Roads (NDOR) has developed and implemented an actuated advance warning dilemma zone protection system. The system continually monitors traffic at an upstream detector as well as at stop line detectors to predict the onset of the yellow indication and provides information to drivers (via flashing signal heads and a warning sign) regarding whether they should be prepared to stop as they approach a traffic signal.

    The system has been documented as being effective at improving traffic safety at isolated signalized intersections where the controller operates in the fully actuated mode. The NDOR is currently considering the feasibility of deploying these devices on its coordinated arterials.

    One objective of this research is to develop a traffic microsimulation procedure for testing the feasibility of deploying the NDOR actuated advance warning system on coordinated arterials. The calibrated traffic microsimulation model will be used to test potential locations of the upstream detector, durations of the lead flash (amount of advance warning time provided to drivers before the green ends), and the maximum allowable headway at the upstream detector location. This will help establish the sets of design parameters for which the system will be beneficial on coordinated arterials. The findings will be used to develop guidelines for the application of the actuated advance warning system so that NDOR can make more informed decisions about where to deploy the system.
    Project Amount
    $ 42,376.75