The Elland Bypass A629 is closed both ways between Calderdale Way and Huddersfield Road.
The main road between Halifax and Huddersfield is closed along Calderdale Way, Halifax Road and Elland Wood Bottom for emergency repairs after a gas main was damaged on Tuesday night.
The damage was by a third party contractor carrying out work in the area.
The road is expected to remain closed for most of today (Wednesday).
Motorists are being advised that this could have knock-on effects around junction 25 of the M62.
Neil Travers, operations manager for Northern Gas Networks, said: “We’d like to apologise for any inconvenience road users may encounter and thank them for their patience as we work to complete this emergency gas work as safely and quickly as possible.”
Anyone that smells gas or suspects carbon monoxide should call the National Gas Emergency Service immediately on 0800 111 999. This line is in operation 24-hours a day, seven days a week.