How do you determine when to use which proposition? (in on at...)

Its easy to say I'm sitting on a box or in a box

But sometimes its confusing

Like for example, do you say -I'm in school Or -I'm at school

-there was an accident on this road Or -there was an accident at this road

  • at means the surroundings of the dam, and on means over the dam surface.
    – Schwale
    Commented Feb 5, 2016 at 13:22

3 Answers 3


Do you drive on the road or at the road?

there was an accident on Dam Neck Road

means somewhere along that road

there was an accident at Dam Neck Road

would mean you are already on a different road which crosses Dam Neck Road and the accident was where the two roads intersect (as you point in the direction of Dam Neck Road)

If there was a specific location

There was an accident at Dam Neck Road and River Street

it would signify the location of the intersection

Additional examples

There is an accident on highway 247
There is an accident on the bridge (this one is tricky)
There is an accident on the off ramp at junction 64

There is an accident at junction 64 on highway 247
There is an accident at the bridge (this one is tricky)
There is an accident at the traffic light


At refers to a specific location, a point on the geography...

... at the intersection of Broad Street and Maple Avenue.

On refers to the road as a surface or as a route.

There was some debris on the road.

We are on the road that takes us into the city.

Thus, we cannot say not OK "there was an accident at the road" not OK because the road is never a point. The road is analogous to a line, straight or curvy.

P.S. But as Peter indicates in his answer, if you're traveling on Broad Street and reach Maple Avenue, where there is an accident at the intersection, you can say:

There was an accident at Maple Avenue

But the sentence above requires the context that you were traveling on a road that intersects Maple Avenue; "at Maple Avenue" is there understood to mean "at the Maple Avenue intersection".



In X is appropriate if you are surrounded on most sides by X, such as in a container, building, etc.

On X is appropriate if you can physically be atop something, or to refer to flat surfaces. Typically you are on a road.

At X is appropriate if X is a place. The notion of a place is a logical construct and while usually associated to specific flat surfaces and buildings, it's a loose association - when we say X is at Y we don't care how X and Y are touching.

Some things can be both places and other things, so sometimes this distinction is blurry. For example, school is a place, as well as a building. So you can be at school or in school.

A road can be considered a place sometimes as well. Typically this happens when an intersection is involved or one cares more about someone or something's location (or place) than the physical orientation against the road.

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