New year, new asphalt.
That’s the 2026 outlook for Legacy Parkway, the long-controversial highway that connects Salt Lake City to Farmington on the edge of Great Salt Lake wetlands. The Utah Department of Transportation will expand the road to three lanes in each direction next year.
“If we didn’t add this lane, congestion would progressively get worse and worse by the year 2050,” UDOT spokesperson Mitch Shaw said. “And, by that time, based on our population models, it would basically be gridlock.”
Shaw also said adding lanes to Legacy in 2026 will allow UDOT to complete the planned widening of Interstate 15 quicker and for about $200 million cheaper.
UDOT published its final environmental study of the Legacy expansion project late last month, finding that the new lanes will crank up noise in some areas and contribute more gunk to Utah’s air.
The Legacy project represents yet another departure from the 2005 agreement that restricted the parkway to two lanes, set a speed limit of 55 mph and banned large semitrucks. Those limitations expired on New Year’s Day 2020, immediately leading to truck traffic and higher speeds.
Two organizations involved in the lawsuit that led to that agreement — Friends of Great Salt Lake and Utahns for Better Transportation — criticized the plan to add another lane.
“What’s missing,” the organizations wrote in a joint letter to UDOT, “ … is the recognition that building more roads only encourages more traffic that continues to predicate more lanes and more deficit spending of taxpayer money that should be invested in improving alternative transportation options for a growing Wasatch Front.”
The 2026 construction will be entirely state-funded to the tune of $65 million. UDOT will add a lane in each direction from the highway’s southern terminus at Interstate 215 to where a third lane already exists near its interchange with I-15. The lanes will be built within the current median.
In the study, UDOT predicts the population of Davis County will grow 37% and that employment there will increase 25% by 2050. Shaw said adding two lanes to Legacy is one piece of the larger transportation demand puzzle. The agency, he said, knows it needs to expand transit service and shared-use paths, too.
UDOT expects that more cars traveling more miles on the highway will lead to increased pollution and greater greenhouse gas emissions, but the study’s authors are banking on stricter federal regulations and improved fuel efficiency in the future to reduce the impact.
For wheeze-inducing pollutants like ozone and particulate matter, UDOT believes the additional lanes will be better for air quality in 2050 than keeping the road as is. Adding the lanes, officials contend, will improve traffic flow and reduce idling.
Lexi Tuddenham, executive director of the environmental advocacy group HEAL Utah, wrote to UDOT saying the expansion would not provide relief from traffic congestion or its related air and water quality issues.
“Instead,” she wrote, “it will only displace these off of I-15 to the neighborhoods, schools [and] businesses adjacent to Legacy Parkway.”
UDOT’s study also predicted the additional lanes will generate more noise in some sections of the road. About 40% of the sites UDOT studied along the parkway would be so loud after the construction, they would be eligible for noise-deadening sound walls.
Shaw said construction on Legacy will start in the spring and should be wrapped up by the end of the year, while the larger I-15 project won’t kick off until summer 2027. Neighborhood voting on whether to add sound walls in areas where UDOT deemed it feasible to build them is ongoing.