ROANOKE, Va. (WDBJ7) - UPDATE:
Exit 143 off of I-51 southbound has reopened, clean-up continues along I-81 following a Thursday morning tractor-trailer accident.
LANES REOPENED: The 581 northbound lanes to I-81 South toward Blacksburg are now open.
According to VDOT a tractor-trailer accident is causing a block along I-81 South to I-581 South and I-581 North to I-81 South.
The North right lane and shoulders of I-81 are closed.
Motorists can expect a mile delay.