Comparative Analysis of Travel Impacts between the Design-Build and Traditional Building Methods

A $25\text{kilometer}$ section of the I-15 freeway crosses the metropolitan region of Salt Lake City, Utah. The Utah Department of Transportation (UDOT) built the road the fast track way: “Design and build.” The project disrupted traffic for four and a half years. Had the freeway been rebuilt by several traditional “design-bid-build” contracts, traffic would have been disrupted for about a decade. This paper compares the disruptive impacts of fast track and traditional construction. Traffic delays, accidents, and emissions estimates for each approach provide a highly detailed assessment of the implications of building quickly. The road closure schedules for each alternative are based on recorded events and UDOT standard practice. The travel modeling is done through VISUM with diurnal traffic assignments. The results show that fast track construction is superior to the traditional approach in terms of user delays. While the impact of emissions and accidents is measurable, it proves to be less significant. The paper reaches the conclusion that the fast track approach to I-15 reconstruction was the right decision because it produced less disruption for travelers than the traditional method.