Developing and Validating a Highway Construction Project Cost Estimation Tool

About the report:

In May 2002, Virginia's Commonwealth Transportation Commissioner tasked his Chief of Technology, Research & Innovation with leading an effort to develop a definitive, consistent, and well-documented approach for estimating the cost of delivering construction projects. A task force that included Virginia Department of Transportation (VDOT) central and district office staff, Virginia Transportation Research Council staff, Commonwealth Transportation Board members, and a metropolitan planning organization member was formed to either locate a well-founded, tested method for estimating project costs that could be adapted for use by VDOT or develop one. The task group found that a VDOT district had been using an estimation worksheet for several years that produced consistent and reliable results for certain types of roadway and bridge construction. The task group determined that no other method examined had the specificity and potential of this tool. The project team expanded the tool by collecting extensive project data and obtaining evaluations of VDOT project management personnel statewide to develop it further. The existing Excel 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 task group also recognized early on that a very strong focus on project scoping was essential to accurate project estimation. A previous VDOT scoping committee had determined that VDOT did not have a consistent, uniform method that was being used statewide to scope projects. As a result, project cost estimates made at the scoping stage often did not hold up over time because key project features were invariably overlooked. The result was inaccurate estimates. Testing of the cost estimation tool was completed in the summer of 2003. Analysis of a sample of completed VDOT construction projects throughout the state showed that the tool yielded results that, on average, differed from actual final project costs by 22 percent. After further modifications, the Project Cost Estimation System (PCES), as it was named, became a fully operational system for VDOT in October 2003. The PCES is composed of three elements: a cost estimation tool, an improved scoping process, and a project development website. The responsibility for maintaining and updating the PCES now rests with VDOT's Scheduling & Contract Development Division.

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