Police are appealing for witnesses to an incident on the A12 at Marks Tey.
Officers are investigating reports a dark coloured Mercedes was driven in a careless or dangerous manner on the A12 shortly before 1.10pm on Thursday, October 27.
The vehicle and a second car, a black Nissan people carrier, stopped on the northbound sliproad at Marks Tey.
There was an altercation involving the drivers. A 50-year-old man from north London was arrested on suspicion of assault and released on bail until January 26, pending further enquiries.
Officers want to speak to anyone who saw what happened or saw the vehicles travelling on the A12.
Contact Pc Ryan Weavers at Colchester police station on 101. Alternatively, contact independent crime-fighting charity Crimestoppers anonymously on 0800 555111 or www.crimestoppers-uk.org