Increasing capacity on 5400 South involves two strategies, Carrillo says, outright widening of the roadway from Redwood Road west and something altogether new to the Beehive State: signalized flex-lanes.

Because widening 5400 South from Redwood Road was not an option, engineers from UDOT and consulting firm Stanley Consultants, Salt Lake City, created flex-lanes—a system to utilize the existing lanes more efficiently during peak-use hours.

A series of 17 signal gantries was installed along a 2.1-mile, east-west section of the road. Each traffic lane has a signal indicating when it is open or closed or operating as a turning lane. A red x or green arrow will indicate whether traffic is permitted in a specific lane.

In the morning, during heavy traffic going east, more lanes will be turned into eastbound lanes, with the opposite occurring in the evening with heavier traffic westbound.

Vance Hanson, a project manager with Stanley Consultants, says the team looked at similar projects in British Columbia and Arizona, but the final design is unique to 5400 South.

"Nothing we were doing here was off-the-shelf," Hanson says.

The roadway proceeds up a grade from Redwood Road, so Hanson says engineers had to decide on the optimal placement of the gantries.

"We decided drivers should be able to see at least three lights ahead of them at all times," he says. "That should be far enough in advance so everyone would know what they were doing."

Hanson says the largest challenge of the project has been getting equipment to interface with existing systems at the UDOT Traffic Control center, where they will be monitored and controlled. The system is in its final phase of testing and is expected to begin operating before October.

West of Bangerter to 4800 West, 5400 South is being widened to seven lanes from five. The project involved acquiring property along the south side of the road, relocating residents and demolishing 38 homes.