Monday kicks off a roughly year-long project to replace the West Bozeman Interchange's two aging bridges with one new structure.
Montana's Department of Transportation says the project will make the bridge less vulnerable to earthquakes and will improve traffic capacity.
There are two phases to the project. Phase one will start Monday and last through August.
Workers will remove the northbound bridge crossing I-90 and traffic will be down to two lanes on the southbound bridge.
Once phase one is complete, construction will begin on the southbound overpass and is expected to end in the summer of 2014.
The two bridges will be replaced by one single structure and include wider shoulders and sidewalks to accommodate bicycles and pedestrians.
It will also boast new traffic signals and a two lane access ramp to Interstate 90.
Those who commute to and from Bozeman on North Seventh will want to pay special attention to a sign on the street's shoulder. It signals big changes for those traveling northbound on the interchange, starting Monday.
Debra Korol leaves her home in Manhattan every morning around 5:30 a.m. to get to her job at Casey's on North Seventh.
She says she saw the sign alerting drivers to road construction but didn't know just how serious the project would be.
"It kind of makes me mad because I could see if they were closing it for a little while to do some renovations but for months? That means I have to re-route my whole trip," says Korol.
Korol showed me possible detours she could take -- Oak to 19th, Baxter or Frontage -- and says it will add at least 10 minutes both ways to her daily commute. That's because northbound motorists won't be able to turn left to get onto I-90 headed west.
"It's inconvenient," states Korol.
But her boss, Casey's manager Ginny Strobel, says she's not concerned when it comes to business.
"We have some pretty major businesses behind [us] and around here and different motels so, I really don't think it's going to impact this area very much," says Strobel.
I talked to business owners on the other side of the interchange who say the project will affect business. Folks at Panda Buffet didn't want to appear on camera but told me they worry customers might find somewhere else to eat.
I stopped some construction workers on their lunch break who say they travel the interchange every day.
"Do you think that's going to impact your travel a lot?" I asked.
"Yeah, it will definitely on our way home from work," replied construction worker Tony Garboden.
"So, what are you going to do?" I asked.
"Have to find another route home," replied Garboden.
But not all motorists say they're concerned.
"I don't really think it will be too much of a problem. I mean, if you can go past the interstate and flip around, it just takes a couple of extra seconds. I don't think that'll be too bad," says commuter Flora McCormick.
MDT officials say if they have to, they might consider allowing left turns onto the interstate after several weeks.
Construction costs are expected to total about $8.8 million.