Motorists who use Interstate 694 in the northeast metro can expect a summer of delays and detours as the Minnesota Department of Transportation (MnDOT) rehabilitates a 6-mile segment of the highway.

Drivers will encounter single-lane traffic in each direction between Hwy. 61 in Maplewood and N. 40th Street in Oakdale beginning in June. It will last through mid-October.

About 62,000 vehicles use the stretch of highway that passes through Maplewood, Mahtomedi, Pine Springs, White Bear Lake and Oakdale, according to MnDOT traffic counts in 2010, the latest statistics available.

The $20 million project includes putting down a layer of asphalt on top of the existing concrete, then placing a new 10-inch concrete surface on top of the asphalt. The asphalt will serve as a "flexible layer" and will allow the adjacent layers to move independently. That is expected to reduce the chances of cracking, MnDOT said.

It also is cheaper than removing and replacing the current pavement, MnDOT said.

Along with new pavement, which is expected to last for 25 to 30 years, MnDOT will reconstruct ramps at Hwy. 36 and White Bear and Century avenues, replacing centerline culverts and guardrails and making bridge and deck repairs. Crews also will construct acceleration lanes at the intersection of I-694 and Hwy. 36.

Some ramps will be closed intermittently, and detours will be posted, MnDOT said.

When the project is done, there will be two lanes open in each direction separated by a cable median guardrail to reduce cross-median crashes. But drivers can expect major delays while the work is in progress and are encouraged to use alternate routes.