Firefighters are battling a grassfire that forced the closure of northbound lanes at Muswellbrook in NSW's Hunter region.
Southbound motorists were being allowed through under police escort on Friday afternoon, the NSW Transport Management Centre said.
Two helicopters and 15 firefighters were battling the blaze at Muscle Creek Road and no properties were under threat, a Rural Fire Service spokesman said.
The fire had burnt through about four hectares by 4pm (AEDT).
Motorists are being advised to allow additional travel time.