Traffic has ground to a halt with long tailbacks on the A12 following an accident.
The dual carriageway is closed in both directions.
Essex HIghways said the incident on the north-bound route was now having an impact on traffic in Colchester town centre.
The incident happened between Junction 26 A1124 Tollgate Interchange and Junction 27 A133 Cymbeline Way. Queues are stretched back to Marks Tey.
HIghways said it was causing delays of upwards of 20 minutes at present while emergency services worked at the scene and it would be some time before the road was cleared.
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