Crews plan to move the Poplar Street Bridge about 9 feet south this weekend, meaning those heading west by taking the Poplar Street Bridge will need to find a different route back over the Mississippi.
That means all eastbound lanes of the bridge will close Friday at 7 p.m., according to Fox2Now.
MoDot said all lanes are scheduled to reopen 5 a.m. Monday.
The Missouri Department of Transportation initially said it would start be closing lanes this week, but because of the heavy rain preparation work was postponed until Wednesday and Thursday nights, a spokesperson said.
"This work is to remove overhead signs and the sign supports prior to this weekend's work to 'slide' the bridge," Andrew Gates wrote in a news release.
The work will ultimately add an eastbound lane.
The area engineer for St. Louis told the St. Louis Post-Dispatch that engineers will use 26 hydraulic jacks to raise the road about an inch and will then slide the road some 9 feet south.
"Even though it sounds cool, it's not going to look terribly cool," Gates told the Post-Dispatch. "It's just going to be so slow.''
MoDOT said earlier this week that if weather allows it three lanes in each direction will be closed from 10 p.m. to 5 a.m. on Wednesday and Thursday night.
Adding the eastbound lane is part of an ongoing project costing some $54 million in hopes of reducing traffic congestion and extending the usable life of the bridge at least another 25 years, the Post-Dispatch reports.
Adding the lane also ties the eastbound and westbound spans of the Poplar Street Bridge together, which MoDOT officials say will make the bridge stronger.