OBRIDGE Viaduct, in Taunton, was closed earlier this afternoon due to a vehicle fire.
Fire crews were called to the incident at 3.25pm and police were also on the scene to close off the road.
A van was well alight when fire crews arrived and the crew cab was severely damaged.
Motorists are reporting heavy traffic and long delays in the area.
Taunton Deane Mayor Libby Lisgo told the County Gazette on Facebook: "Just taken 40 mins from town centre to Priorswood."
Brian Pook, who was walking nearby, said: "Traffic is queued from Wickes roundabout all the way up East Reach - horrendous."
The cause of the fire, which is now out, is believed to have been accidental.