The Missouri Department of Transportation plans to close all lanes of westbound Interstate 70 in part of downtown St. Louis for a period this weekend.

MoDOT says the closure is necessary while girders are installed for a new overpass at Walnut Street. Westbound I-70 lanes will be shut down from 8 p.m. Friday until around noon Saturday between Pine Street and the Poplar Street Bridge.

Eastbound lanes will also be closed for up to 15 minutes at a time. The Eads Bridge also will be shut down for the same period.

MoDOT will detour westbound traffic, but motorists who can use alternatives such as Interstate 64 or Interstate 44 are encouraged to do so.