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Utah is about to add another 80-mph speed zone on Interstate 15, this one near St. George — but it also plans to lower limits in another stretch there.
That is one of the final areas to be evaluated for possible higher speed limits under a new state law that has led to numerous 80-mph zones on Utah's rural interstates, and 70 mph zones on urban Wasatch Front freeways.
The Utah Department of Transportation is proposing to raise the limit from 75 mph to 80 mph from the State Street interchange in Washington City north to milepost 22.6 near Leeds, according to documents scheduled to be taken up Friday by the Utah Transportation Commission.
At the same time, UDOT plans to establish a 70-mph limit between the Arizona border and milepost 11.6 north of St. George. Speed limits in that stretch vary between 75 mph near the border, and 65 mph in areas through St. George.
Robert Miles, UDOT director of safety and traffic, said the change will smooth the speed limit through St. George and provide better safety.
The speed limit of 75 mph will remain between the end of the new 70-mph zone and the beginning point of the new 80-mph zone.
Miles said the proposed changes come after his agency studied how fast people are actually driving in the area, the design of the roads, accident history and traffic and road conditions.
He said he does not expect the new 80-mph zone to actually increase speeds in the area much, because studies show average speeds now are already that fast — and the change will essentially make legal the speed that most people travel.
Miles adds that studies after speed-limit increases in others areas show that they raised actual overall speeds by 1 or 2 mph.
"There's not a lot of difference in the before and after when speed limits have been raised," he said. "We're not seeing a 5-mile-per-hour increase in general when we raise the limit 5 miles per hour."
The plans for the speed-limit changes are scheduled to be presented at a Utah Transportation Commission meeting Friday in Hurricane. Afterward, cities and counties in the area will be notified officially about the changes.
Miles said the changes likely "will happen pretty quickly after that. We have been coordinating with local law-enforcement agencies down there, so we have been working behind the scenes to make sure we have the right understanding of behavior."
States that have any speed limits of 80 mph or faster include Utah, Idaho, Montana, Nevada, South Dakota, Texas and Wyoming, according to the Governor's Highway Safety Association.
Utah is one of 17 states that have top freeway speed limits of 70 mph in urban areas.
The higher speed limits added over the past year have been controversial because highway death rates increased dramatically during that stretch.
However, UDOT said most of the increased fatalities have come not on freeways, but on secondary roads — so highway officials say the higher speed limits and increased death rates are unrelated. It blames higher death rates on such factors as people not wearing seat belts and on distracted driving.
Miles said UDOT will continue to evaluate speed limits statewide and will make changes as conditions and driving habits warrant.