iron bridge; railway bridge
Refers to a bridge made of iron or steel, often specifically a railway bridge. In modern usage, it can be any metal bridge, but the railway association is strong.
This iron bridge was built in the Meiji period.
I can hear the sound of a train crossing the railway bridge.
The train crossed the river over the iron bridge.
A long iron bridge spans this river.
The company planned to build an iron bridge over this valley.