Most of the studies that evaluated the benefits of incident management have used analytical techniques such as queuing and shock wave analyses to assess the impacts of incidents with and without incident management on delays and queues. These analytical methods were applied to basic highway segments with no considerations of the facility configurations. In addition, the analyses in most cases assumed a constant typical capacity on these segments to represent the prevailing capacities without the use of the Highway Capacity Manual (HCM) procedures. These studies also assumed that the input parameters such as the reduction in capacity due to incidents andincident durations are deterministic rather than stochastic variables. This paper investigates estimating the benefits of incident management by combining the HCM freeway analysis procedures, detailed ITS data archives, and the consideration of the stochastic variations of key inputs to the analysis rather than using deterministic values. The results from this analysis methodology are compared to those obtained using the simple deterministic queuing analysis procedure, which has been used extensively in past studies. The analysis reveals that the HCM procedures produce similar results as queuing analysis for simple basic freeway facilities. The results for more complex cases indicates that queuing analysis produces lower incident delays relative to the HCM procedures, due to not modeling the interactions between segments of different types and geometries. Higher delay reductions resulted from incident management are estimated for one-lane blockage incidents with the use of stochastic incident attributes compared tousing deterministic incident attributes.
Samenvatting