The M8 motorway ground to a halt in Glasgow on Sunday afternoon after a multi-vehicle collision.
The accident, at about 2pm, blocked the motorway westbound after junction 22.
Traffic Scotland said on Twitter that diversions had been put in place.
A Police Scotland spokesperson said: “Emergency services are currently in attendance at an incident on the M8 near to Junction 23 westbound, Govan, Glasgow, to which police were called around 2.05pm.
“There are no further details at this time.
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“The M8 westbound is closed prior to Junction 23 and traffic is being diverted via at the M8/M77 junction.”
The westbound carriageway remained blocked after junction 22 at 4.45pm, Traffic Scotland said on Twitter.
Motorists were facing estimated delays of 55 minutes.