The new Osage River railroad bridge is scheduled to open Monday at a ceremony in Osage City.
Officials from MoDOT, Amtrak and Union Pacific have said the bridge will eliminate the last major "bottleneck" between St. Louis and Jefferson City, where two railroad tracks funneled to one to cross the river.
New track and signaling devices have been installed at both ends of the bridge.
The old bridge will be retrofitted to be aligned with the new bridge and tracks.
The work will be done ahead of schedule since the original completion date was the second week in December. This is despite suffering a one-week delay because of the flooding earlier this year.
The total cost for all the work originally was estimated at $24 million to $25 million, but MoDOT officials now think the work could come in $3 million to $4 million under budget.