This week, the Minnesota Department of Transportation will put the finishing touches on the new Cedar Lake Regional Trail bridge carrying pedestrians and bicyclists over Hwy. 100 in St. Louis Park.

Then the agency will start razing the Hwy. 7 bridge as part of the $60 million project to upgrade Hwy. 100 to three lanes in each direction between I-394 and 36th Street. Part of the work was done last year with a new bridge and interchange put in at Minnetonka Blvd. The rest of the work, including extra lanes and a new overpass and interchange at Hwy. 7, will be completed this construction season.

That news has some motorists wondering why the Hwy. 7 bridge over Hwy. 100 was shut down last fall when demolition was not planned until this spring.

"Highway 7 over Highway 100 was closed all winter when there was no work done on the bridge," one Drive reader commented. "I have heard it was closed completely because there was no pedestrian and bike crossing due to the Cedar Lake Trail bridge replacement. Did MnDOT really give priority to a couple pedestrians and bikes over the 30,000 vehicles that use Highway 7 each day?"

No, says MnDOT spokeswoman Bobbie Dahlke.

"Although a lot of people use that trail — it's not just a few — that was not the reason we didn't demo it or let people on it," she said.

Here's why: MnDOT closed the structurally deficient Hwy. 7 bridge in October when the new Minnetonka Blvd. overpass opened. The soil surrounding the Hwy. 7 bridge was bad and not conducive for building a new bridge. Crews dug out the old soil and replaced it with good soil and sand, which is heavier and necessary to support the foundation for the new bridge, Dahlke said.

"We had to let that sit for three to four months. And while we did that, it was not safe to put the weight of vehicles on the bridge," she said.

Now that the dirt has settled, MnDOT will bring in the wrecking ball and knock down Bridge No. 5462. The work begins Friday and will have a big impact on the 132,000 commuters who travel Hwy. 100 each day.

Squeeze coming

Starting Monday, northbound drivers will be squeezed into two lanes between 36th Street and Cedar Lake Road. Southbound drivers have until Thursday before they lose a lane. The two-lane-in-each-direction configuration will be in place through late fall.

Then at 10 p.m., Hwy. 100 in both directions will be closed between I-394 and the Crosstown Hwy. 62 until 5 a.m. next Monday as crews begin taking down the crumbling 80-year-old Hwy. 7 bridge. A second weekend closure is scheduled April 22 -25 to allow them to complete that task. Motorists will be detoured to I-394, I-35W, Hwy. 169 and the Crosstown.

The new Cedar Lake Trail will open Friday.

Bridge 5462's removal is another step forward in ridding drivers from one of the worst pinch points in the west metro. For historians, it means taking out the last vestige dating to the Great Depression. It was built as part of the largest Works Progress Administration (WPA) project of the time. The overpass, and the one at Minnetonka Blvd. replaced last year, were among the first cloverleaf interchanges in the state. It's kind of sad to see the bridge go, but oh so necessary. So long Bridge 5462.

Follow news about traffic and commuting at The Drive on startribune.com. Got traffic or transportation questions, or story ideas? E-mail drive@startribune.com, tweet@stribdrive or call Tim Harlow at 612-673-7768.