Any time the Minnesota Department of Transportation begins a construction project, it warns drivers to "Know Your Route." Next week, when a major bridge and pavement reconstruction project begins on Hwy. 169, drivers all across the entire west metro may want to heed that advice.

On Jan. 10, MnDOT will shut down the Nine Mile Creek bridge between Bren Road and 7th Street/Lincoln Drive on the Minnetonka-Edina border for nine months, meaning that nearly 90,000 motorists who cross it each day will have to find another way to get around.

At the same time, the ramp from westbound Interstate 394 to southbound Hwy. 169 will be closed for the duration of the project. And to throw another monkey wrench into the mix, southbound Hwy. 169 will be reduced to a single lane between Betty Crocker Drive to just south of the I-394 interchange. The idea is to limit the number of southbound motorists using the portion of Hwy. 169 between I-394 and 5th Street/Lincoln Drive and steer them onto I-394 and I-494, said MnDOT's David Aeikens.

"We want to keep people who don't live, work or have business out of the area," he said. "I would not use Hwy. 169 if I didn't have to. It's going to be challenging."

Before traffic thickens after the holiday lull, this might be the week to experiment with alternate routes before chaos hits next week. Officially, the detour for northbound drivers is to follow the Crosstown east to Hwy. 100, then north to I-394 and back west to Hwy. 169. Southbound drivers are being sent west on I-394 then south on I-494.

Naturally those routes are going to see increased traffic volumes, but so are Hwy. 7, Hopkins Crossroad, Excelsior Blvd., Minnetonka Blvd. and Cedar Lake Road as drivers seek short cuts. "Think about where you're going and what route you take," Aeikens said. "Try new routes. Practice them, and if that doesn't work, try another one."

Transit riders also will feel the impact. SouthWest Transit, as it has been doing over the past two years, will send most of its downtown routes along I-494 up to I-394 where buses can jump into the HOT lane, said CEO Len Simich.

Minnesota Valley Transit Authority buses from Shakopee to Minneapolis will follow Hwy. 13 over to I-35W. "Buses will operate on schedule as best as they can," said spokeswoman Robin Selvig. But "we don't know exactly what the impact will be."

One thing is certain: Things are likely to get worse before they get better. Over the next three months, MnDOT will demolish the current bridge, drive pilings and put in new culverts. Once the frost leaves the ground in the spring, the scope of the work expands. The highway will be down to one lane in both directions between Hwy. 55 and the Crosstown as the agency rehabs 6 miles of pavement. Ramps at 7th Street, Excelsior Boulevard, Hwy. 7, Cedar Lake Road and 36th Street will be closed for two weeks at various times through the summer.

Aeikens admits it's a lot to stomach for a part of town that just suffered through two straight seasons of major road work on Hwy. 100 and I-494. By cramming all this into nine months, it will all be done in one season instead of the three that would have been needed had MnDOT worked on one side of the Nine Mile Creek bridge and then the other.

The end result will be a raised bridge looking like a causeway over the low marshy area, longer acceleration and deceleration lanes at Cedar Lake Road and smoother pavement.

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.