Evaluation of Rural Interstate Work Zone Traffic Management Plans in Iowa Using Simulation

Traffic levels on Interstate Highway 80 in eastern Iowa increased percent between 1988 and 1997, with summer traffic volumes approaching 40,000 vehicles per day. These traffic levels and the expected continued growth create special problems when developing a work zone traffic management plan (WZTMP) at a long-term work zone. Motorists at past work zones on this highway have experienced long delays. A methodology for evaluating the cost-effectiveness of alternative delay-reducing WZTMPs was developed and tested on a past work zone to determine its effectiveness. Using Traffic Software Integrated System (TSIS) 4.2, four WZTMPs were modeled to evaluate their effectiveness at reducing motorist delay. These models were based on a case study of a long-term work zone on Interstate 80 in 1997, where queues developed on 34 different days from May 31, 1997 to September 13, 1997. Of the competing alternatives, the most cost effective alternative is to direct the contractor to implement a nonstop work schedule until project completion. The results for this alternative indicated that about 9,044,000 vehicle-minutes of delay could have been avoided. This represents an 86% reduction in delay reduction compared with the “do-nothing” alternative. This methodology was developed as a planning tool to determine the potential benefits of alternative traffic management plans at work zones. Highway agencies using this methodology can determine the potential cost-effectiveness of alternative WZTMPs at upcoming work zones.