For at least eight weeks, motorists who use the Rex Whitton Expressway westbound might want to find another route.
Missouri Transportation officials said Friday that, beginning at 9 a.m. Wednesday, the westbound U.S. 50/63 driving lane will be closed over Lafayette Street.
The passing lane will remain open, leaving one westbound lane available.
"We are expecting congestion, especially for peak traffic flows in the morning," MoDOT Resident Engineer Terry Imhoff told the News Tribune Friday.
A MoDOT news release said congestion also could be a problem. Travelers driving westbound on U.S. 50/63 into Jefferson City will experience delays during peak traffic times, especially during morning and afternoon rush hours.
At the same time, the westbound on-ramp at Clark Avenue also will be closed.
Lafayette Street will be closed between Dunklin and Elm streets - just south of the expressway - for the next year.
Beginning at 6 a.m. Thursday, the westbound off-ramp from U.S. 50/63 to Lafayette Street will be opened to traffic - for those who want to go north on Lafayette.
All of the work is part of the $20.3 million project to add a diamond interchange between Lafayette Street and the highway, to add exit- and on-ramp lanes to the expressway and to improve several bridges between Monroe Street and Clark Avenue - including the already-completed Chestnut Street overpass.
The project is to be finished by the end of next year.
Imhoff said part of the work involves dropping the expressway about five feet, so the current hill between Monroe and Lafayette streets isn't quite as steep.
That work begins with closing the westbound outside, driving lane.
In about eight weeks - in mid- to late September, assuming the weather cooperates - both westbound lanes will be closed while the current bridge deck over Lafayette Street and Wears Creek is lowered and replaced.
During that work, Imhoff said, westbound drivers will use the off- and on-ramp of the new interchange, which will be wide enough to carry both westbound lanes of traffic.
After the westbound side of the overpass is finished, he said, it will be used to carry the eastbound expressway traffic while the current eastbound overpass lanes are replaced with a new, lower deck - and the westbound motorists will continue using the ramps as their part of the highway.
Meanwhile, Imhoff suggested, motorists might want to consider taking the McCarty Street exit by Walmart, Eastland Drive or Clark Avenue, to avoid the congestion in the construction zone.
Electronic message boards have been placed along the route to inform motorists of the closures associated with the work.
"We appreciate the public's patience and understanding while we work on this phase of the project, which will greatly improve traffic flow and safety in the area when completed," Imhoff said in the news release.
More information about the interchange project, including traffic impact summaries and weekly construction updates, is available at modot.org/central/major_projects/LafayetteInterchange.htm.
Motorists also can call 1-888-ASK-MoDOT or visit MoDOT's Central District on Facebook or Twitter for additional details.