The A303 is closed in both directions while a lorry is recovered from a large ditch.
The road is closed between the junctions for the B3089 near West Knoyle and the A350 at Chicklade.
A spokesperson for Highways England said: “A HGV involved has gone down a ditch and the closure is required in order to facilitate the safe recovery of this.
“Traffic is being diverted locally, eastbound via the B3089 and the A350, westbound via the reverse of this.”
“This incident is likely to cause delays. Please allow additional travel time, and consider an alternative route if possible.”
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