Determining Highway Project Contract Time from Project Duration Estimates

Contract time determination (CTD) by state DOTs is critical to a typical design-bid-build project due to its profound impacts on stakeholders in various aspects, such as the actual amount of time allocated to the contractor, contracting parties’ costs, and motorists’ traveling experiences on roads constructed under traffic. Reviewing DOTs’ CTD manuals and guidance shows that determining contract time is more complex than only estimating a reliable project duration from technical inputs such as work quantities, which has been the focus of previous studies. The type of contract time (e.g., working days or calendar days) affects contractors’ schedule risks, and external factors such as political commitments often affect highway projects significantly. However, those issues were rarely considered in past studies. Furthermore, a systematic procedure for determining contract time from a project duration estimate and effective supporting tools are lacking in DOTs’ current practice. This study proposed such a procedure incorporating typical constraints of highway projects identified by reviewing CTD-related documents and conducting seven face-to-face interviews with CTD experts. Other contributions include designing an accompanied computation algorithm to automate the process and developing a freely available Microsoft Excel tool to help DOT practitioners implement the proposed procedure in their operations.