Obviously there's no traffic-dodging involved with this cache. The map might make it look like the cache is in the middle of this rather busy road, but there's always that third dimension...
This is an example of a bowstring bridge, similar to the one crossing the A14 near Milton, just north of Cambridge. This one isn't as pretty, but it's made of nice ferrous metal (there's a clue there somewhere!)
The cache location is accessible from the northwest or southeast, although the access from the southeast is much closer - a cache and dash can be had here.
The cache is a 35mm film canister with a nice strong magnet attached to it. It's just visible to the passers-by below, and should be easy to find, although not with your eyes.
Please bring a pen or pencil as the cache container is too small to house one!
Happy hunting!