Please do NOT attempt this one from the A12, access is from above along a little used route, Coles Oak Lane. There is plenty of room for parking.
The A12 is a major road in England. A trunk road for most of its length it runs from London to Great Yarmouth in Norfolk. The road forms part of the unsigned Euroroute E30. Unlike most A roads, the A12 (together with the A14 and the A55) has junction numbers as if it were a motorway.
The 84 km section of the A12 through Essex has sections of dual two lanes and dual three lanes with eight changes in width between the M25 to Ipswich. It was named as Britain's worst road because of "potholes and regular closures due to roadworks" in a 2007 survey. The A12 is covered by the Highways Agency and A12 and A120 Route Management Strategy.
This is a bridge that I had thought about placing a cache at for a while, however now due to very recent works, access has been made better. Once you have found the cache, please replace back as found.