Developing and Validating a Tool to Estimate Highway Construction Project Costs

Abstract

In May 2002, Virginia's commonwealth transportation commissioner directed the Virginia Transportation Research Council (VTRC) to develop an improved method to estimate the project costs of the Virginia Department of Transportation (VDOT). After an effort to look across the United States and within VDOT for proven estimation methods, the study group found that VDOT's Fredericksburg district had been using an estimation worksheet for several years that produced consistent and reliable results. The study group concluded that no other methods examined had the specificity and inclusive nature of this tool. VTRC staff and the Fredericksburg staff who had developed the model expanded it by collecting extensive project data and obtaining evaluations of VDOT project management personnel statewide. The existing worksheet with roadway and bridge estimates was expanded to include construction engineering, to be applicable for Interstates and to generate estimates for right-of-way and utilities costs. Data on completed projects were collected from all VDOT districts to help calibrate the model further to account for cost variations across the state. The study group recognized early that a strong focus on project scoping was essential to ensuring accurate project estimation. Therefore, the group relied on input from the VDOT scoping committee that had been charged with exploring and developing recommendations for improving the scoping process. Testing of the tool was completed in the summer of 2003. Analyses of many completed VDOT construction projects showed that the estimation model yielded results that on average differed from actual final project costs by 22%.