So you think Super Bowl detours were bad? And last summer's Lowry Hill Tunnel project? Fasten your seat belts.

This week's ramp closures and detours are just a foretaste of what's coming in mid-June. That's when the Minnesota Department of Transportation will shut down the main ramp leading from northbound Interstate 35W into downtown Minneapolis — for four months.

MnDOT, city officials and many downtown employers are bracing for epic traffic jams and urging commuters to take transit or work at home — and even dangling huge parking discounts for carpools.

The I-94/I-35W interchange is being rebuilt as part of a $239 million makeover of I-35W between downtown and 43rd Street. But that is just one of four work zones that I-35W drivers will encounter this summer. Overlapping projects with lane closures of their own will be underway simultaneously in Burnsville and Roseville and just past the I-35W/35E split in Forest Lake.

"We want to keep as many people off I-35W as possible," said MnDOT spokesman Dave Aeikens.

By far the biggest pinch point will be downtown, where MnDOT will slim down I-35W from 10 travel lanes to five and shut the main ramp, pushing 42,500 drivers daily to the one remaining access point: the winding ramp at 3rd Street and Washington Avenue behind U.S. Bank Stadium.

The flyover bridge from northbound I-35W to westbound I-94 will be out of commission. So will the outbound ramps to southbound I-35W at 12th Street and 4th Avenue S., leaving 4th Street and Washington Avenue as the two exits.

"We realize these are big impacts," said MnDOT spokesman Aaron Tag. "It's a big project in an urban setting and it's hard to keep traffic moving when you rebuild this infrastructure."

That has Dan Tysver, who commutes from southwest Minneapolis to his job as a patent attorney in the Capella Tower on 6th Street, thinking about his options. "I'm just going to buy a raincoat and bike most of the time," he said.

One Apple Valley resident is thinking about getting on I-94 at Snelling and coming in from the east rather than enduring the stoplights on Cedar or Hiawatha avenues.

Breaks for buses

Transit will also be affected, but MnDOT and the city of Minneapolis have plans to make it move faster than regular traffic, said project manager Nariman Vanaki.

One lane on Park and Portland avenues will be reserved exclusively for buses during morning and afternoon rush hours. The I-35W ramps at 31st Street will be open to buses only. Some signals will be retimed to give buses priority.

Even for an agency used to navigating around construction zones, this summer will be by far the most difficult, said David Hanson, Metro Transit's assistant director of field operations.

Metro Transit runs 700 buses carrying 14,000 riders along the I-35W corridor each day. The agency plans to add 50 more daily trips on 10 routes. The extra service will cost $6 million, with MnDOT covering half.

"We will get riders from Point A to Point B, but it will be a challenge," Hanson said.

With nearly two-thirds of its riders taking buses that run on the I-35W corridor, the Minnesota Valley Transit Authority is gearing up, too. It is adding buses to current routes, debuting new service and opening a park-and-ride lot on Pillsbury Avenue in Burnsville to relieve overcrowding at the nearby Burnsville Transit Station. In Eagan, a new route bypassing I-35W will go the 46th Street Station where riders can get on the Blue Line.

Incentives for carpools

There also is a big push to boost carpools in Minneapolis, which includes 780 registered carpools in city-owned Ramps A, B and C near Target Center. MnDOT and the city will offer $20-a-month parking for approved carpools that bypass I-35W, scoot over to Hwy. 100 and come in on I-394. The usual rate is $99.

"There has been a big uptick in interest at outreach meetings we've had," said John Barobs, a spokesman for Move Minneapolis, the city's commuter resources bureau. "This is getting real."

Move Minneapolis will hold a transportation summit on May 9 at Orchestra Hall to help commuters explore their options, he said.

Early warning signs

While the push is on to steer commuters to transit, MnDOT has added some help for drivers. It installed dynamic signs near 66th Street in Richfield that will flash how much time northbound drivers will need to reach downtown via I-35W, or by taking westbound Crosstown Hwy. 62 to northbound Hwy. 100 to eastbound I-394.

"We're trying to help people make decisions before they get stuck in traffic," Vanaki said.

A few lanes are being added: on westbound Crosstown from Valley View Road to Hwy. 100; on I-394 from downtown to Hwy. 100 and on northbound I-35W from 31st Street to the 3rd Street exit.

When MnDOT adds, it also takes away. Drivers on westbound I-94 have already lost the ramp at 11th Street and soon will have one less lane between Hwy. 55 and 3rd Avenue. Eastbound drivers will lose the ramp to southbound I-35W.

Minnesota River bridge

More misery looms for south metro drivers in July when MnDOT begins replacing the bridge spanning the Minnesota River.

North of downtown, five weekend closures in July and August will send I-35W drivers on a detour so MnDOT can resurface the freeway. Further north, a resurfacing project between Hwys. 97 and 8 in Forest Lake already has drivers feeling the pinch.

Why do all these projects at once?

"If we did them one at a time, it would take 20 to 30 years," Aeikens said, turning I-35W into a perpetual construction zone. "We decided to do them, get them done and deal with it in a shorter period of time."

Tim Harlow • 612-673-7768