The A12 has re-opened southbound between J28 and J27 near Colchester after a road traffic collision lead to long delays.
Highways England and Essex Police deployed resources to the scene to deal with the incident which is thought to have involved a lorry.
A spokesman for Highways England had advised motorists to take alternative routes.
He said: "For traffic approaching the closure locally, you are advised to expect disruption with extra journey time and may potentially have to re-route your journey.
"If travelling towards this area from further afield, you may wish to consider an alternative route, allow extra travel time and follow guidance from our on-road variable message signs and media."
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