Why can Edina quickly plow its streets, but Minneapolis can't?

You're driving on nearly any Minneapolis residential street. Your coffee is spilling; your head is bobbing, and if you've got anything hanging from the rearview mirror, it's swinging wildly as you bounce through a moonscape of rutted ice and snow.

Then you cross, say, Xerxes Avenue. Suddenly, your tires caress pristine pavement and you're rolling in a snow-free Shangri-La.

What changed?

You crossed from Minneapolis into Edina. If you'd have driven from St. Paul into West St. Paul, same phenomenon.

You could compare almost any suburban residential street with almost any residential side street in Minneapolis or St. Paul and you likely get the same result: The cities' streets are a mess. Still. A week after the snowstorm.

Why?

'Parking emergency'

"It all gets down to parking and vehicle storage issues," said Margaret Anderson Kelliher, public works director for Minneapolis. "In Minneapolis, we have residential parking year-round, and usually on both sides of the streets, and Edina can restrict that."

Like many suburbs with an abundance of driveways and garages, Edina has a set of winter parking restrictions that wouldn't fly in Minneapolis and St. Paul, where neighborhoods were designed long before the era of multi-vehicle households. Edina bans overnight parking all winter and declares a snow emergency any time there's about 1.5 inches of snow.

Brian Olson, Edina's director of public works, said the ability of suburbs to order all vehicles off a street is a game changer.

"It's not just the dedication of our workers, but also those parking restrictions that allow the streets to be cleared as well as they are," he said.

Minneapolis and St. Paul generally hold off declaring an emergency until there's a healthy layer of plowable snow on the ground — about 3 inches for St. Paul, while Minneapolis steers clear of offering a threshold.

"A snow emergency is really a parking emergency," said Sean Kershaw, St. Paul's public works director.

Cars must move

Adding to the challenge: Without fail, not all vehicles are moved before the plows come through, and that can make a bigger difference than you might think.

"They have to get their cars out of the way," said James Campbell, a professor at the University of Missouri-St. Louis College of Business Administration who has researched logistics and operation modeling for all sorts of large-scale operations, including snow removal.

In abstract computer models and real-world experience, efficiency and effectiveness of plowing can plummet when even a fraction of vehicles remain, Campbell said.

Physics of heavy snow

In order to "throw" the snow from the plow blade off the street — as opposed to just shoving a growing pile forward — a plow must reach a certain speed. That might be a challenge for a big plow truck that requires room to accelerate and safely brake. Add a parked vehicle to that side of the street, and the momentum is lost.

Making matters worse: The heavier the snow, the faster the plow must go to throw it effectively. And the most recent snowfall was heavy — as anyone who tried to shovel it can attest.

"This was the fourth-heaviest — by weight — snow in Minnesota in January in recorded weather history in Minnesota," Kershaw said.

During the recent snow emergency, Minneapolis wrote 4,103 tickets and towed 485 vehicles. St. Paul ticketed 2,155 vehicles and towed 430.

Alleys, sidewalks

There are more reasons why it's harder to clear — and keep clear — city streets.

For example: