Thornton Interchange between Rigby and Rexburg opens

Idaho Transportation Department workers and public leaders gathered for the grand opening ceremony of the Thornton Interchange on U.S. 20 Friday.

The final action was to remove the barriers from the interchange, which immediately opened the driveways to drivers.

This marks the end of a 16-year project to build a series of interchanges to improve safety and movement on the U.S. 20 corridor between Idaho Falls and Sugar City.

“We can’t build them all at once but we’ve just taken one at a time. Started in Idaho Falls and moved north. So we’ve slowly completed that effort,” said Wade Allen, the ITD engineering manager.

“Doing this project — and all the projects between Idaho Falls and Sugar City — it’s to provide safety to the traveling public,” said ITD district No. 6 engineer Jason Minzghor.

The Thornton Interchange is the seventh interchange constructed along the route. The interchanges replace 18 ground level intersections that have been closed. Despite traffic more than doubling on the corridor, these interchanges have cut the number of fatalities in half, and drastically reduced the rate of serious injury crashes.

“This is a great effort. Great relief to have it done. We get to open it. It’s not still being worked on in the winter. This is great to have it done this time of year,” Allen said.

Starting in 2000, the Idaho Transportation Department replaced 18 dangerous intersections with seven interchanges. The Thornton Interchange gives drivers safe entrance on and off the 28-mile stretch of U.S. 20.

“We spend a lot of money to do this, but we can save a lot of lives,” said the project inspector Gregg Bowman.

While the projects have increased traffic by 115 percent, the ITD says the projects have decreased serious-injury crashes by 75 percent and have cut fatalities by more than half.

“We recognize the impact it will have on our community, in the sense of economic development and safely moving traffic. We anticipate great things to happen in the south end of the county,” said John Webber, a Madison County commissioner.

The total cost of all seven of these interchange projects was about $85 million. Final landscaping of the Thornton Interchange will be finished in the spring.

Here is a list of the completed projects within the last 16 years:

Sugar City-Salem (Exit 338) – Completed in 2001 County Line (Exit 318) – Completed in 2001 Driggs-Jackson (Exit 339) – Completed in 2001 St. Leon (Exit 311) – Completed in 2004-2005 Hitt (Exit 313) – Completed in 2004-2005 Menan-Lorenzo (Exit 325) – Completed in 2010-2011 Thornton Interchange (Exit 328) – Completed in 2016-2017