In british terms the difference between underbridge and overbridge
is that underbridge is a bridge that allows traffic to pass under a road, river, railway etc while overbridge is a bridge that allows traffic to pass over a road, river, railway etc.
underbridge
English
Noun
(
en noun)
(British) A bridge that allows traffic to pass under a road, river, railway etc.
The underneath of a bridge
Usage notes
Where a bridge takes one form of transport over another it is both an underbridge and an overbridge, depending on the reference level. For example, where a road passes above a railway, the bridge is an overbridge from the point of view of the railway, and an underbridge from the point of view of the road.
See also
*overbridge
overbridge
English
Noun
(
en noun)
(British) A bridge that allows traffic to pass over a road, river, railway etc.
Usage notes
Where a bridge takes one form of transport over another it is both an overbridge and an underbridge, depending on the reference level. For example, where a road passes above a railway, the bridge is an overbridge from the point of view of the railway and an underbridge from the point of view of the road.
See also
*underbridge
*overpass