Warning: Rough road ahead.

The grinding that will reshape two commuter arteries that carry a combined daily average of about 25,000 motor vehicles and 1,200 bikes begins Monday at E.46th Street. and Park Avenue.

Starting from that point, Hennepin County maintenance crews will push north on Park for about a week, grinding away about 1-1/4 inches of aging blacktop near the road edges and less toward the middle. Crews will work in three to four-block sections, and repaving with a fresh coat of asphalt will start around the 17th. The work will stop where Park crosses Interstate 94 because the downtown section was repaved last year.

Crews then will turn around and mill southward on Portland Avenue 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 between milling and repaving, and will experience delays because the road will be narrowed to two driving lanes at a time. It's the first such resurfacing since 1997.

The repaved road surfaces will later be restriped with significant changes from the current three lanes in each

direction. Most of the roadways will be narrowed to two lanes, except in downtown and possibly near Lake Street. Bikers will get wider travel area.

County Transportation Director Jim Grube said last week's community meeting has the county still mulling two potential changes to its recommended design. He said it's possible that the Portland Avenue bike lane will join Park in being shifted from the left side of the roadway to the right side. The previous design started the lane on the left, 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.