Delay Estimation and Optimal Length for Four-Lane Divided Freeway Workzones

Vehicle delay is one of the most serious impacts of highway workzones on existing traffic operations. The present study provides a comprehensive and detailed estimation of traffic delay due to a freeway workzone where the roadway in one direction is closed and the traffic usually on the closed roadway is diverted to share the roadway in the opposite direction. The total delay was decomposed into speed reduction delay and congestion delay. Different procedures were developed to estimate speed reduction delay for several roadway conditions. A mathematical model was developed to find the length of the queue upstream of a workzone and a procedure was generated to estimate daily congestion delay under any given condition. Alternative roadway closure patterns along the length of a given project were evaluated in terms of traffic control cost and additional road user costs. The optimal workzone length for a given project was studied. Procedures were developed to determine the optimal workzone length.