Boaters are used to seeing "No Wake" signs on rivers and lakes and know that they need to move at a slow enough speed to keep their waves from splashing against the shoreline.

But a "No Wake" sign on a highway?

Dana Fox was mystified by the one she spotted attached to the exit 234B sign (5th Street) while driving westbound on I-94 in Minneapolis.

A no-wake zone on a highway or freeway is aimed at snowplow drivers, and it warns them not to create a wake or rooster tail of snow on the side of the road, said Minnesota Department of Transportation (MnDOT) spokesman Kent Barnard.

In no-wake zones, plow operators reduce their speeds and gently pile the snow along the shoulder or bridge deck. MnDOT crews come along later to remove the excess snow during cleanup operations.

The premise is to prevent snow plowed off one road from falling onto other nearby roads.

That's the reason for the no-wake zone on northbound Snelling Avenue just north of the Minnesota State Fairgrounds in Falcon Heights. There, plows going at full-bore could cause snow cleared from the main road to spill onto E. Snelling Drive, a frontage road that runs parallel to Snelling Avenue.

In Minneapolis, moving too fast near exit 234B could kick up a wave and force snow off the side of the I-94 overpass and onto the light-rail tracks, the Hiawatha Bike Trail and 17th Avenue S. below.

Drivers decry delays

Speaking of snowplowing, MnDOT got an earful and more (read profanity) from hundreds of irked motorists who complained that the agency didn't get the roads cleared fast enough during Thursday morning's rush-hour snowstorm, spokeswoman Bobbie Dahlke said.

True, roads were an absolute mess, as witnessed by the 67 crashes and 106 spinouts or vehicles going off the road that the State Patrol responded to between 5 and 10:30 a.m.

One of the most spectacular wrecks involved scores of vehicles slipping and sliding and crashing on southbound I-35 at Hwy. 8 in Forest Lake. The daunting scene prompted authorities to shut down the freeway for a couple of hours.

Like cities that declare snow emergencies and put winter parking rules in place, perhaps MnDOT should be able to declare a snow emergency and ban driving until highways and freeways have been plowed curb to curb. That would allow plows to clear the roads before motorists clog them up and mash the snow down.

"It does take more resources to clear compacted snow than fluffy snow," Dahlke said. "When snow is compacted, we have to apply more and different material to lift snow from the pavement so we can plow it. The application process takes more people and more material."

I, like anybody else, pay taxes and want the roads plowed so my 20-minute commute doesn't turn into a three-hour tour (sing theme from "Gilligan's Island"). But when Mother Nature decides to let the flakes fly in copious amounts at inopportune moments, Shakopee Mayor Brad Tabke has it right.

"We need to have better options in our region like transit, telecommuting and variable schedules to handle nasty days like today," he wrote in his "Why was MSP traffic so awful today? In defense of MnDOT" blog post. "And a little patience."

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.