Main Street viaduct replacement project starts Sept. 13 in downtown Kansas City

Main Street traffic over Interstate 670 in downtown Kansas City will be detoured for up to 50 days beginning Sept. 13 for a $2.75 million bridge replacement project.

The new bridge is not expected to be completed until early to mid November, according to the city’s Public Works Department. Main Street traffic over I-670 will be rerouted to Oak and Baltimore streets during construction.

The work also will require single-lane closures of Interstate 670 to allow repairs to the retaining wall and construction of the bridge support columns.

City engineers have said previously that the Main Street bridge, which was built when the downtown freeway loop was constructed in the 1960s, has about 10 years left of useful life. Rather than replace it after the planned streetcar line opened, the decision was to do it now to avoid disrupting the new system.

The city will pick up some additional expenses for both the new Main Street bridge over I-670 and its other crossing over Interstate 70 to the River Market. Both bridges previously were owned and maintained by the state, but after the replacement project is completed, those responsibilities will be transferred to the city.

The new bridge over I-670 will include some important improvements for pedestrians. Besides the decorative trim being designed by El Dorado, the sidewalks will be widened from the current 6 feet to 8 feet on the west side and 18 feet on the east side. HDR Engineering also is part of the bridge design team.

“We’re looking at making it a very walkable bridge,” Sean Demory, a spokesman for the Public Works Department, said in an earlier interview.