The northbound M6 was closed by traffic officers from National Highways at 6.38pm on Monday after an incident involving a heavy goods vehicle which saw at least 300 litres of diesel spill onto the carriageway between Junction 5 at Castle Bromwich and Junction 6 for Spaghetti Junction.
All three lanes of the carriageway are closed and traffic officers involved with contractors in a substantial clean-up operation and work to assess the road surface for damage.
It has caused huge tailbacks on the motorway, with delays of at least 90 minutes between Junction 4 for the M42 and Junction 5, and traffic officers were turning vehicles around from the back of the queue to exit at Junction 5.
Disruption is expected until about 10.30pm.
A spokesman for National Highways said: “The M6 in the West Midlands is closed northbound between Junction 5 Castle Bromwich Interchange (Birmingham (E), Sutton Coldfield A452) and Junction 6 Gravelly Hill Interchange aka Spaghetti Junction (Birmingham (Cen) A38 (M), Birmingham (NE) A38).
“This is due to a substantial spillage of diesel (at least 300 litres) from a heavy goods vehicle.
“National Highways traffic officers are on scene and contractors are being despatched to clear the spillage and assess the road surface for damage.
“A substantial clean-up operation will be required.”
A diversion route has been put in place, with motorists urged to follow the route marked with a hollow circle symbol on road signs, then exit at Junction 5 and at the roundabout at the end of the slip road, take the third exit on to the A452 northbound.
From there, motorists should cross under the M6 and, at the Spitfire Island, bear left on to the A47 westbound, then continue to the Bromford Lane Roundabout and take the second exit to remain on the A47 westbound, before continuing to the StarCity Roundabout (with the B4137) and take the third exit.
From there, follow the B4137 Cuckoo Lane past StarCity to the traffic light controlled junction with the A5127 Lichfield Road, then turn right at the junction on to the A5127 Lichfield Road and continue to Salford Circus roundabout, before taking the first exit from the roundabout on to the link road to the M6 and bear left at the fork to re-join the northbound carriageway.
A spokesman for National Highways said: “Road users intending on using this section of the M6 are strongly urged to consider alternate routes if possible as this closure is expected to be protracted.
“The closure is causing delays of over 90 minutes on the M6 northbound between J4 Coleshill Interchange (The SOUTH WEST, Birmingham (S), Solihull, Birmingham Airport, NEC M42) and the closure at J5.
“Delays are likely on the approach to this closure, with additional journey times also expected on diversion routes.”
For more information, go to x.com/HighwaysWMIDS.