The A14 is partially blocked in Northamptonshire following a three-vehicle pile-up during Monday's morning rush-hour.
Traffic was queueing both ways on a 11-mile stretch of the carriageway between junction 12 for Corby and junction 15 at Toll Bar Lane.
Highways England reported delays of up to 50 minutes at 8.30am.
Queues are also building on the A45, A6116 and A605 with traffic struggling to join the A14 via the eastbound entry slip.
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A spokesman for Highways England warned drivers to steer clear of the area while the central reservation barrier is repaired.