Highway 4 Accident Sponsored by: By B.J. Hansen Published Dec 28, 2010 06:40 am Updated Dec 28, 2010 06:43 am Copperopolis, CA — The CHP is on scene of a reported collision on Highway 4 near the Diamond 20 subdivision. An ambulance has been dispatched to the area. Travel with caution on Highway 4. The accident is not blocking traffic.