The A12 was closed in both directions following a police incident.
Emergency services were at the scene of an incident near Marks Tey.
A spokesman for Essex Police said the closure was put in place after they were called to reports of concerns for the welfare of a woman at about 10.25am.
The spokesman confirmed that the woman was in the care of the ambulance service.
National Highways said traffic was being diverted via the exit and entry slip roads and that there were delays of at least 40 minutes above normal travel time.
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