They cost $216 million. But the four freewaylike interchanges added to Bangerter Highway last year have shortened afternoon peak-time commutes by eight minutes, new data says.
“That’s actually impressive because that still includes some big backups” daily at regular intersections with signals that tend to slow the flow between the new interchanges, said Brad Palmer, program manager for the Utah Department of Transportation’s Region 2.
UDOT traffic studies say that cut the afternoon commute on the highway between Interstate 80 near Salt Lake City International Airport and Interstate 15 in Draper from an average 42 minutes to 34.
“We hope to get that down to 22 minutes eventually,” when Bangerter becomes a full freeway, eliminating all intersections with traffic lights, Palmer said.
The new study didn’t count the additional time savings from previous freewaylike intersections installed in recent years at 7800 South, Redwood Road and 600 West.
Next year, UDOT plans to start construction to convert three more intersections into freeway interchanges at 6200 South, 10400 South and 12600 South. (Some work to relocate the Jordan Aqueduct at 6200 South and Bangerter has already begun). Those projects are estimated to cost about $147 million.
With those three additional new interchanges, Bangerter will have two long sections of freeway — from 5400 South to 9800 South (which will still have a signal intersection), then from 9800 south to 13400 South, said Marwan Farah, Bangerter Highway project manager for UDOT.
No funding has been identified to convert the 9800 South intersection into an interchange, but Palmer said “it is at the top of the list” in priority for conversion after next year’s projects — and would allow a 10-mile stretch of full freeway on Bangerter.
Cutting eight minutes off a full-route trip on Bangerter now adds up, considering 60,000 cars use the highway each day, Farah added.
“Not only does it improve speed, it helps the environment” with fewer emissions from cars stuck in congestion or idling at stop lights, he said.
“It has improved safety,” he adds — although UDOT says three years is required for reliable studies on changes in crash data. “But we’ve eliminated T-bone collisions” by eliminating left turns off the main body of the highway. It also should reduce rear-end collisions from traffic that no longer must stop at lights.
UDOT figures that because of growth in the western and southern reaches of Salt Lake County, Bangerter will carry 100,000 cars a day by 2040, a 67% increase.
Farah says not only will a full freeway help handle that, but it is expected to eventually shift about 20,000 cars a day from nearby Interstate 215 and help improve flow there.
Palmer said the new interchanges have also reduced congestion on cross streets between 10% and 20%.
Benefits are especially noticeable at 5400 South in Taylorsville.
The average afternoon commute on 5400 South between Redwood Road and Bangerter dropped from eight minutes to five. “Essentially, the afternoon peak disappeared — and we just have regular traffic there now,” Palmer said.
That reduction also allowed UDOT to remove a complicated and controversial “ThrU Turn” nearby on 5400 South and 4015 West. It had prohibited left turns at that intersection, forcing U-turns down the road and special signalized “bulb-out” intersections. Many businesses complained the design blocked easy access to them.
With benefits from converting to a freeway, why not change all the intersections more quickly? “Show me the money,” Farah said — adding it isn’t there, and the agency builds what it can with its resources, weighing priorities among projects statewide.