Brigham City • Neighbors of Legacy Parkway lost a last-ditch attempt Friday to extend a 15-year deal designed to protect adjacent Great Salt Lake nature preserves by banning big-rig trucks and allowing just a 55 mph speed limit and only two lanes in each direction.

As they made pleas to the Utah Transportation Commission, the Utah Department of Transportation announced that it has legal power over that decision — not the commission — and said the truck ban will disappear Jan. 1 and, at the same time, the speed limit will rise to 65 mph.

Woods Cross City Administrator Gary Uresk had asked officials, “Please do not turn Legacy into another I-15.”

Angie Keeton, founder of Save Legacy Parkway, said new communities had turned their front doors toward the scenic byway because of its beautiful views, trails, no big rigs, dark-sky lighting, rubberized asphalt that dampens noise and avoids sound walls, low speeds and a limit of just four total lanes. She said most residents did not realize all that was temporary.

Such amenities were ordered for 15 years in a settlement of lawsuits by environmental groups that had blocked construction of the 11.5-mile highway in Davis County.

Keeton quoted a 2005 law that encoded the deal, saying the amenities were needed to protect adjacent wetlands and the area’s environment.

“The 2,100-acre preserve is still there. The Great Salt Lake is still there, although threatened,” she said. “Therefore, the environmental conditions which were used as justification for the Legislature’s own requirement to ban heavy trucks continue to this day and will into the future.”

Keeton also presented documents from the original deal that she said allows — but does not mandate — UDOT to raise speed limits and erase the truck ban after appropriate studies.

“We respectfully request that the commission ensures that a study identifying the need for change — offering all potential change options and outlining all potential negative impacts — to be completed before any action is taken to change the current status of the parkway,” she said.

But Jason Davis, UDOT deputy director, said the agency has final power to raise speed limits after consulting with the commission, and said Legacy’s limit will be raised to 65 mph when the 15-year-deal officially expires Jan. 1.

He also said extending the truck ban would have required action by the Legislature, but it killed two bills seeking such extensions amid arguments that allowing trucks, higher speeds and potentially adding lanes may be needed to handle growth. The Utah Trucking Association said it waited patiently to use the road and needs it for such things as easier access to the new inland port.

“Unless something had changed in the last legislative session, the truck prohibition was going to end on Jan. 1, 2020," Davis said. “Nothing changed, so that will occur.”

Robert Miles, UDOT director of traffic and safety, said the agency had performed studies about whether raising the speed limit on Legacy would be safe and determined that setting it at 65 mph would be appropriate.

(Rick Egan | Tribune file photo) Sign on the Legacy Parkway, stating the 55 mph speed limit, Dec. 6, 2018. The lowered speed limit will disappear Jan. 1, 2020, along with a ban on big-rig trucks.

He said studies show that most drivers already go between 65 and 70 mph there, despite the lower limit, creating dangerous speed differentials with slower-moving vehicles following the law. Raising it to 65 mph, he said, would result in more of the traffic traveling at roughly equivalent speeds.

Raising the speed limit by 10 mph is not expected to make those cars go 75 to 80 mph, he said. “Our experience is it usually raises the overall speeds by 1 or 2 mph."

Uresk told officials at the meeting that most cities had given up hope for extending the truck ban when the Legislature rejected it, but said they now urge raising the speed limit to no more than 60 mph — and presented resolutions from Woods Cross, North Salt Lake and West Bountiful seeking that lower limit.

Uresk said both raising the speed limit and erasing the truck ban will be “a double whammy” for neighborhoods along the parkway, which he added may suddenly have big rigs doing 70 mph, erasing the quiet of the area.

Uresk also said he has heard many interests urging a widening of the road to handle more traffic and growth. He encouraged UDOT and the commission to consider and study how that might affect the area’s environment on the shores of the Great Salt Lake.

Despite the apparent final announcements Friday, possible legal challenges still loom.

The Sierra Club of Utah, which led lawsuits that helped create Legacy’s eco-friendly design, says it is not ruling out new legal challenges.

“Litigation is still a possibility," said Ashley Soltysiak, chapter director for the Utah Sierra Club. “We haven’t ruled out anything at this point.”