The Utah Dept. of Transportation has completed the Utah County I-15 Corridor Expansion project. Construction was finished in an unprecedented 35 months, making I-15 CORE the fastest billion-dollar public highway project ever built in the United States.
I-15 CORE reconstructed 24 miles of freeway from Lehi to Spanish Fork.

Photo courtesy of HDR

I-15 CORE reconstructed 24 miles of freeway from Lehi to Spanish Fork and widened the freeway by two lanes in each direction.

The project widened the freeway by two lanes in each direction; replaced the original asphalt with new 40-year concrete pavement, extended the Express Lane from Lehi’s Main Street to Spanish Fork and rebuilt or replaced 63 bridges and 10 freeway interchanges.


The project was led by Fluor Corp. working with the Utah offices of Ames Construction Co. Inc., Ralph L. Wadsworth Construction Co. Inc. and Wadsworth Brothers Construction Co. Inc. The consortium included more than 30 subcontractors.

“We worked closely with Provo River Constructors to employ innovation at an unprecedented level to ensure we delivered this project in record breaking time and under budget,” said Todd Jensen, I-15 CORE project director. “We used the same innovative techniques to minimize the usual delays associated with construction projects.”

One of the most significant achievements of the I-15 CORE project was the innovative methods employed to keep traffic moving throughout construction. Work activities were scheduled around the clock in order to meet the aggressive schedule, but the majority of lane and exit closures—more than 90%—were scheduled during overnight hours to reduce traffic delays.

Innovative traffic patterns, including lane shifts and splits, were used to keep as many lanes open as possible while maintaining safety for construction workers and allowing work to continue.


During construction, the I-15 CORE project achieved several notable milestones:


• It moved the Sam White Bridge, the longest two-span bridge to be moved by self-propelled modular transporters in the western hemisphere, into place over I-15 in one night.


• It constructed a new continuous flow intersection, the first of its kind in Utah County, at University Parkway and Sandhill Road to reduce congestion at one of the busiest intersections in the county.


• It constructed a new diverging diamond interchange at 500 East in American Fork, only the third DDI completed in Utah County.

• It completed more than 90% of I-15 closures and restrictions during overnight hours to reduce inconvenience to the public.

• It implemented lane splits to keep existing travel lanes open as much as possible while paving continued in the middle of the freeway.


• It installed advanced traffic management system devices—including 93 sensors, 36 cameras, 22 ramp meters and four permanent variable message signs—to help UDOT engineers monitor traffic, respond to incidents and ensure the transportation system functions as efficiently as possible to keep traffic moving.