Beginning Wednesday, traffic on some lanes on 5400 South in Taylorsville will travel one direction during the morning rush hour and the opposite way in the evening.
Overhead lane indicator lights for the new "flex lanes" have been on for the past week to allow drivers to become accustomed to them, but no lanes have changed direction yet.
Those changes start Wednesday.
"Flex lanes will allow us to open a lane when we need it, where we need it," said Brandon Weston, project director for the Utah Department of Transportation. "Their implementation will efficiently improve traffic flow along 5400 South between Redwood Road and Bangerter Highway."
During the morning rush hour, 5400 South will have four eastbound lanes, a center turn lane and two westbound lanes. In the evening, that reverses with four westbound lanes, two eastbound and one center turning lane.
The stretch has overhead electronic lane control signs every 500 feet Â with green arrows in lanes where traffic is allowed, red X's where it is not, yellow X's where traffic should begin moving out of lanes because directions are about to change, and yellow left-turn markers for a center turn lane.
Flex lanes avoid widening the road in the area and are possible where roads are busy in one direction in the morning and in the other direction in the evening.
Tim Rose, deputy director of UDOT's Region 2, has said that not only are these the first flex lanes in Utah, but they also are the first flex lanes in America with a left-turn lane in the middle Â which Taylorsville wanted to help businesses there.
He said that made the project more complicated than expected and led to a year of delays from problems with hardware and software.
An animation of how the lanes work is online at udot.utah.gov/flexlanes.
Another nearby section of 5400 South also has big changes coming in the next few weeks. UDOT plans to open the state's second "ThrU Turn" intersection there at 4015 West inKearns before Thanksgiving, said spokesman Adan Carrillo.
It will not allow any left turns at the intersection to help speed traffic. Instead, cars seeking to go left must first proceed straight through the intersection and then make a U-turn at a special signal about 500 yards down the road, come back to the intersection and then make a right turn.
This year UDOT installed its first ThrU Turn Â called Michigan U-Turns in other parts of the nation Â at 12300 South and State Street in Draper.
The Kearns ThrU-Turn is part of a road-widening project on 5400 South between Bangerter and 4800 West, which will now have seven lanes. Carrillo said it is expected to be substantially completed by Thanksgiving. However, crews will add a protective "microsurface" to that stretch next spring.
The widening through Kearns required demolishing three dozen homes and a few businesses.
See how they work
To view an animation of how the new flex lanes work, go to udot.utah.gov/flexlanes.