(WRCB) – Tennessee Department of Transportation crews will close the Highway 41 bridge over the Tennessee River in Marion County.

TDOT officials say the bridge will remain closed until the new replacement bridge is completed.

Crews say problems with the bedrock at the location of the new bridge calls for blasting and drilling.

Because crews must excavate, drill, and blast to construct the new bridge piers, TDOT engineers say it is best for the safety of the public and the workers that the old bridge is closed to through traffic while this work is being performed. 

A detour route that will add an additional 1.5 miles to the current route will be posted. 

Because of the additional excavation and testing needed, the completion date of the bridge replacement project has been extended to February of 2014. 

Although motorists should plan for the existing bridge to be closed until that date, TDOT will inspect the existing bridge once the new piers are constructed to determine if it can be re-opened prior to completion of the new bridge. 

The prime contractor for the $21.5 million project is Britton Bridge, LLC of Mt. Juliet, Tennessee.