# "Move over the bridge" vs. "move on the bridge"

The train is moving under the bridge.

I know this is fine.

• The train is moving over the bridge.
• The train is moving on the bridge.

You can use either, depending on context.

If you are talking about a single point in time, it's "on". if you're talking about an action, ie something that takes a finite time, then it's "over".

eg single instant of time:

"Where is the train?" "It's on the bridge."

Alternatively, for an action (taking some time):

"When will the train arrive?" "In a couple of minutes - it just has to travel over the bridge and then it will be in the station."

This seems inconsistent, but if you used "on" in the above sentence, it doesn't get across the idea of the train coming onto the bridge, travelling the length of the bridge, and exiting the bridge. Eg if i said

"The train will be here soon - it just needs to travel on the bridge."

This sounds like the train will drive onto the bridge, stop, and then the bridge itself will start moving and carry the train into the station, which isn't going to happen (probably - these sorts of bridges exist for cars and might exist for trains, but they are very rare).

I think this is because "on" implies that the object is not moving (relative to the thing that it is on): either because we're talking about it at a single instant in time, or because it has actually stopped.

Conversely, if you used "over" for a single instant of time, like this

"Where is the train?" "It's over the bridge."

This sounds like the train is floating in the air, or perhaps (more plausibly) on another bridge which crosses above the first bridge.

• I was watching a video where they said "Over the bridge". My doubt is resolved now.
– user168878
Commented Apr 7, 2016 at 8:15
• Editing my answer... Commented Apr 7, 2016 at 8:22
• "it just has to travel OVER the bridge" is this synonymicall to "it just has to travel ACROSS the bridge"
– user168878
Commented Apr 7, 2016 at 8:33
• In this context, i think the meaning is the same, yes. Commented Apr 7, 2016 at 8:47
• Note by the way that if we were talking about something that didn't touch the bridge, like an aeroplane, you would always say "over", not "across". This applies for a single point in time and for an action, eg "The aeroplane is over the bridge.", "The aeroplane will fly over the bridge.". So i think the meaning is only the same for things which are in contact with the bridge. You could use "across" or "over" for people walking over the bridge for example. Commented Apr 7, 2016 at 8:50

'On' is a prepositon of location; and so anything that is stationery, we will say 'On the bridge'. Also for something moving, as long as it is between the two ends of the bridge, we sill say 'On the bridge. 'Over' is a preposition of location and a propostion of direction.

1. as a preposition of location, we would say 'The aeroplane is over the bridge'
2. as a preposition of direction, we would say 'The aeroplane flew over the bridge' meaning that it flew from one end of the bridge to the other as a part of its flight. Similarly, when someone walks across the bridge,we focus on the movement, and not the location, we would say 'He walked across/over the bridge.' I hope this helps.