There aren't many bridges around New New Zealand like this, so it's a bit of a novelty.
Bridge 95 carries the road (where you are standing) on the lower level, and a few metres above you is the railway line.
Don't worry, there is no danger from trains here because the railway is inaccessible from here, and the cache is nowhere near the tracks. Your feet will be planted on the ground to find this cache.
BYO pen. Don't drop the cache.
Happy caching!