Traffic delays are expected to intensify this weekend as work continues on the pedestrian tunnel underneath U.S. 93 near Grandview and Four Mile Drive.

The project is expected to enter its second stage just after midnight Friday as workers begin to install the box culverts that will give the tunnel its form.

Montana Department of Transportation spokeswoman Lori Ryan said contractors will work 24 hours a day for about 10 days to complete the tunnel project.

Thus far, the construction has resulted in the closure of one southbound lane while both northbound lanes have remained open.

That will no longer be the case Saturday as travel in each direction on U.S. 93 will be limited to one lane and the speed limit will be reduced to 25 miles per hour through the gravel surface of the 1,000-foot construction zone.

Motorists also will not be able to make left turns from U.S. 93 to Four Mile Drive (which leads to the Kidsports complex) or the Grandview Drive entrance to Flathead Valley Community College during the 10-day duration of the tunnel installation.

The Montana Department of Transportation recommends that drivers use alternate routes if traveling through the area.

Detour signs have been placed north and south of the construction zone.

Kalispell Police Chief Roger Nasset said there has been somewhat of an increase in low-impact collisions on the highway.

“Most of them have been rear-enders at this point, people driving up behind other people and not realizing how close they are till it’s too late,” he said.

Nasset said there isn’t necessarily a correlation between the construction and the collisions, but added that some of the incidents might be due to drivers “gawking” at construction or a lack of attentiveness in general.

An increased number of vehicles on the road also might be a factor, he said. Still, Nasset said drivers should keep their eyes on the road, especially when construction is causing deviations in normal traffic flows.

“People certainly need to be more attentive,” he said.

The final phase of the pedestrian tunnel is expected to be completed later this month with the installation of bike-path connections on each side of U.S. 93.

When finished, the 140-foot-long tunnel will connect the Kidsports complex and Flathead Valley Community College. LHC Incorporated, which is based north of Kalispell, is the lead contractor for the project.