Get ready for some grinding and bumping on Portland and Park avenues in Minneapolis come Monday.

The twin commuter arteries that carry a combined daily average of 25,000 motor vehicles and 1,200 bikes are getting a reshaping to make them calmer and more bicycle-friendly.

First up: grinding off pavement last applied in 1997. That will leave the thoroughfare with bumpy surfaces until fresh asphalt is applied. Finally, the roads will get a restriping that owner Hennepin County and city traffic planners hope will change the roads' character.

Three lanes of traffic will be narrowed to two for much of the length of the avenues between the edge of downtown and E. 46th Street, while cyclists will gain buffer space. The speed limit will drop from 35 to 30 miles per hour.

The daily grind will start on Park, working north, erasing about 1¼ inches of blacktop near the road edges and less in the middle. Crews will work in three- to four-block sections. Repaving with a fresh coat of asphalt will start around the 17th, according to county officials. The work will stop where Park crosses Interstate 94 because the downtown section was repaved last year.

Crews then will reverse direction, milling the pavement southward on Portland starting at Washington Avenue and working all the way south to Crosstown Hwy. 62.

Drivers aren't being detoured, but they'll experience bumpy pavement in sections after milling and before repaving. There also will be delays because the road will be narrowed to two driving lanes at a time.

County Transportation Director Jim Grube said last week's community meeting has the county still mulling two potential changes to its recommended design. The bike lane on Park Avenue will be shifted from the left side of the roadway to the right, and Grube said it's possible that the Portland Avenue bike lane will be shifted in the same way. The previous design started the lane on the left, where it is now, but shifted to the right side after traffic diminishes near E. 36th Street.

Grube said the county also is reconsidering whether the roadways need three full lanes in the area of Lake Street.

Steve Brandt • 612-673-4438