Nightime detours are scheduled through Thursday evening, detouring drivers off southbound I-81 until the Christiansburg exit.
Traffic will be detoured at exit 132, Dixie Caverns unto Route 11/460 and then back onto I-81 again at exit 118 for Christiansburg. The detour will begin at 9 p.m. each night and continue through morning at 6 a.m.
Crews will be removing the Friendship Road bridge.
The detours are part of ongoing construction to build a truck climbing lane between mile markers 120 and 125 on southbound 1-81.
Signs and message boards will be displayed to alert drivers to the detour information.
The full project is expected to be completed in November of this year, although this specific detour will end Thursday.