The roadway between Wallsburg and the northeast end of Deer Creek will be reduced to a single lane between 10 p.m. and 6 a.m. on weeknights, 11 p.m. and 9 a.m. Saturdays and 10 p.m. and 9 a.m. Sundays while flaggers guide drivers through one-way alternating traffic, according to the Utah Department of Transportation.

The project will involve a two-lane northbound route being built on the mountainside above the existing route — which will become the southbound roadway — to address increased traffic caused by growth in the Heber Valley and Park City.

UDOT Region 3 spokesperson Wyatt Woolley said a large portion of the Wasatch Back workforce commutes from Utah Valley and experiences traffic jams when U.S. 189 merges into a one-lane road between Rainbow Bay and the northeast edge of Deer Creek Reservoir.

“We’re fully aware of the traffic needs and the commuter travel, and so we’re hoping that this project will help alleviate a lot of that,” he said.

Safety is an additional concern on the stretch of roadway, which is sandwiched between the mountainside and the reservoir below.

Significant crashes along the route can lead to serious injuries and sometimes death, Woolley said.

“And unfortunately, that has happened in some cases, and so by separating the lanes completely and having physical distance and space between the two, the likelihood of serious crashes and incidents is much lower,” he said.

Building the northbound portion of the road will involve cutting into the slope and building a barrier to protect the existing roadway from rockfall, Woolley said. UDOT said some phases of the project will include controlled blasting with brief canyon closures.

UDOT aims for a fall 2027 completion date.