At/For a Distance Of

Question

Somebody asked me about the usage of the word distance in a sentence. I have my own ideas about it, particularly the difference between at a distance of and for a distance of.

Unfortunately, I’m afraid that the whole answer is in fact connected to something else: a bit of knowledge of road markings perhaps. So I hesitate to talk about only the grammar aspect.

My friend wants to express this:

Do not paint 50 m on the right and left sides from the ends of the ramp, and plus the width of the ramp.

My friend thinks she can say this:

Do not paint the edge line of the road along every ramp at a distance of 50 m on the right and left turns.

This is how far I’ve gotten in reconstructing it in my head:

Do not paint the edgelines of the road for a distance of 50 m on both sides of a ramp

Am I still on the right track?

Answer 1

As far as at vs for goes at specifies a point at which something is important. For specifies a length over which something occurs. I ran the car for a distance of 5 miles. I stopped at a distance of 10 miles from home.

As far as your requirement goes I'd propose something like this:

Road edge lines shall terminate at a distance of 50 meters plus half the ramp width measured from the center of the ramp on both sides of the ramp-road intersection.

(Requirements should be phrased in the positive rather than the negative)

Answer 2

Regarding the requirement "Do not paint the edgelines of the road for a distance of 50 m on both sides of a ramp", a painter could satisfy it by painting edgelines for a distance such as 49 m or 51 m. The directive also uses both where either might be needed. Anyhow, to express the idea that no edgelines should be painted in the last 50 m, say something like:

Within a distance of 50 m (plus ramp width) from the end of a ramp, do not paint an edgeline on either side of the ramp roadway.

Note, I've interpreted the original requirement's "and plus the width of the ramp" phrase as indicating that the proscribed distance is 50 m plus the width of the ramp.

Edit: From Jim's answer I gather that the edgelines in question are painted (or not painted) on the through road rather than on the ramp exiting from that road. As Barrie suggested, a diagram (eg, showing the lines and the ramp as a tee from one lane of a divided highway) might be needed before a concise but accurate description can be written.

Answer 3

"For a distance of" states a physical range over which an action takes place.

Marathoners run for a distance of 26.2 miles.

The car skidded for a distance of 50 kilometers.

"At a distance of" shows a distinct point distanced from a one or more points of origin.

The car came to a stop at a distance of 50 kilometers from where the driver first hit the brakes.

The star Feronymous can be seen at a distance of 764 light years from either of the planets Pheloboron and Thetuclas.

In the OP's example, using the former would refer to the action of painting continuously over an area of 50 meters.

The latter is unable to be used in the OP's example because there is no single point to which it can refer. The side of the ramp contains multiple points of origin, and a point 50 meters from the side of the ramp will differ with the particular point of origin from which it is distanced. The example means to reference all such points 50 meters from the side of the ramp.

Neither phrase properly expresses the OP's intended meaning.