Sean Demory of the City Public Works Department, said the closing should occur this fall and be completed by the end of the year. 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.
The $3.6 million bridge project has stirred a small communication controversy because the timing of its replacement is linked to construction of the new streetcar line that will follow Main Street for much of its route between Crown Center and the River Market.
At one point, el dorado, the architecture firm working on the project, said one reason the bridge was being replaced was to support streetcars. That assertion clashed with earlier claims by streetcar backers who said a significant advantage of their plan was it would not require reinforcing existing bridges, making it cheaper to build than a heavier light-rail line.
City engineers however, say the Main Street bridge, which was built when the downtown freeway loop was constructed in the 1960s, had about 10 years left of useful life. Rather than replace it after the streetcar line opened, the decision was to do it now to avoid disrupting the new system.
The city's assessment about the bridge nearing the end of its useful service was supported by the Missouri of Department of Transportation. Davis also pointed out the Main Street bridge crossing Interstate 70 into the River Market, which also will be used by the streetcar, is not being replaced.
The confusion about why the downtown bridge was being replaced has caused some political stress for Kansas City Councilman Russ Johnson, a fervent supporter of the streetcar plan. Johnson was among those who pointed to the advantage of lighter streetcars not requiring significant improvements to bridges and streets.
David Dowell, the el dorado principal working on the bridge project, could not be reached for comment.
Johnson said the backlash was one reason he's taking a lower profile on the proposal to replace the terminals at Kansas City International Airport with a single-terminal design. Johnson is chairman of the Council Transportation Committee and the airport is in his district.
The city will pick up some additional expenses for both the new Main Street bridge over I-670 and its other crossing 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," Demory said.