West-metro commuters faced an agonizingly slow commute Monday morning as an ill-timed storm conspired with planned road construction to snarl freeway traffic all the way from Rogers to Maple Grove.

The morning commute on Tuesday should be better, with two lanes instead of one southbound lane open in the construction zone.

"But drivers should anticipate there will be slowdowns there," said MnDOT spokesman Kevin Gutknecht. "If they can leave earlier or take an alternate route, they really should do that."

The issues on Monday morning rippled out from a much-awaited construction project to expand a 5-mile length of Interstate 494 between the Fish Lake Interchange and Hwy. 55, one of the metro's most notorious bottlenecks. The northbound lanes had been closed to traffic over the weekend to prepare for the project.

According to the plan, the road was to reopen Monday morning with two lanes carrying southbound traffic and one for northbound traffic. But southbound drivers found only one lane open between the I-94/694/494 split and Rockford Road.

The result was a rush hour with traffic plugged up for miles. At times, the 10-mile trip from Hwy. 101 in Rogers to the split was more than 30 minutes, more than twice the normal travel time.

What happened? The two-lane/one-lane plan relied on a movable barrier and markings to guide cars into the right lanes.

But heavy rain on Sunday night prevented MnDOT from putting down the striping needed. Because some of the barriers protecting bridge pier struts and overhead signs had been removed, MnDOT closed one lane to prevent motorists from getting too close to them, said spokeswoman Bobbie Dahlke.

"Unfortunately, motorists were unaware of the situation and traffic configuration until they encountered it this morning," she said.

The problems also were felt on Hwy. 169 from Hwy. 610 in Brooklyn Park down to I-394 as commuters scooted east to avoid the mess on I-494.

The Monday evening commute was less vexing because two northbound lanes were open between Hwy. 55 and the Fish Lake Interchange. On Tuesday morning southbound traffic will have two lanes open and northbound traffic will have one, the MnDOT says. The arrangement reverses for the afternoon commute.

Here is the plan moving forward: MnDOT will make the traffic switch overnight. All southbound lanes will be closed from midnight to 5 a.m.

A movable barrier will be set up on the northbound lanes, allowing for the planned traffic configuration to be in place.

There will be two lanes in each direction on I-494 between Hwy. 55 and I-394.

Staff writer Mary Lynn Smith contributed to this report.

Tim Harlow • 612-673-7768