Part of the A12 is closed between junction 15 Margaretting and junction 16 Chelmsford following a serious collision in the early hours of this morning. The emergency services are on the scene and motorists are being urged to avoid the area. An Essex Police spokesman said: "We are currently at the scene of a serious collision involving two cars on the northbound carriageway of the A12. "Emergency services are working at the scene and roads policing officers closed the road and turned traffic as quickly as possible. "Please avoid the area if you can and thank you for your patience.