And the number of fatalities dropped from 15 to seven. "That's less than half," Ahmad Jaber, an engineer for the Utah Department of Transportation, told the commission.
So he joked, "The lesson is the more construction you have, the fewer fatalities you will have."
Jaber compiled the statistics at the request of the commission, which wanted to see how safety was affected by the $1.1 billion project that rebuilt 26 miles of I-15 from Lehi to Spanish Fork.
Commissioner J. Kent Millington asked if serious accidents were reduced because people had to drive more slowly with construction.
"I think they drove more carefully because of more narrow lanes, and cars were closer together," Jaber said.
While serious accidents decreased, overall accidents along the stretch increased from 3,560 to 4,175, Jaber said. That calculates to about a 17 percent increase.
"You would expect to have more[crashes] in a construction zone," said Commission Chairman Jeffrey Holt, adding that the overall accident increase was not a surprise but the decrease in serious accidents and fatalities was a pleasant one.
The commission asked UDOT to also study accidents there over the next 34 months to compare post-construction safety with prior periods.
The rebuilding project is scheduled to have its formal ribbon cutting next week, although all lanes were essentially completed and opened to traffic last month.
The project added two lanes in each direction along the 26-mile stretch, rebuilt 10 freeway interchanges and replaced or modified 63 bridges.
Crews used 2.6 million square yards of concrete, which could pave a sidewalk from coast to coast. The project used 7.7 million tons of dirt, which could fill Brigham Young University's Marriott Center 13 times. It also required 6.6 million man-hours of work about the same as the 7 million man-hours needed to construct the Empire State Building.