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I got a task which I don't know how to save some labor work.

So I have two shapefiles in hand. One is roadway shapefile and the other is sidewalk shapefile. My task is to identify where there is only one-side sidewalk. The problem is when I created the sidewalk file, I didn't record the direction. Even if I did, I still can't come up with a way to automatically identify the roadway parts with sidewalks on one side.Is there anyway to make the identification easier? The only thoughts I have right now is to go through the sidewalk file and pick out the one-side sidewalks one by one.

Thanks for any of your thoughts.

Here is a screenshot.The red line represents sidewalks and the blue line represents the center line of roadway.

enter image description here

12B01
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    Could explain what you mean by "one-side sidewalk"? A picture would be great. – Paul Sep 05 '13 at 23:32
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    Is your sidewalk layer a line or polygon? – artwork21 Sep 06 '13 at 01:17
  • The sidewalk is line layer. There are sidewalks on both sides of the roadway for some places. For the other places, there are either no sidewalk or sidewalk only exits at one side of the roadway – 12B01 Sep 06 '13 at 13:50

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What's your data store? If I'm understanding the question, you could probably buffer each road line by about twice the distance away you expect the sidewalks to be and get the count of sidewalk lines contained by the buffered shape.

Russell at ISC
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  • Thanks for your reply! But buffer will only counts the total number of the sidewalks. What I want to do is to pick out those locations with sidewalk only at one side of the streets. So I can propose to construct sidewalk on the other side of streets to allow pedestrian to walk on both sides of the same roadway. – 12B01 Sep 06 '13 at 13:53
  • Shouldn't the count be one if there is a sidewalk on one side and two if there are sidewalks on both sides? Assuming you query "contains" and not "intersects", and that sidewalks are segmented the same way that streets are. – Russell at ISC Sep 06 '13 at 15:17
  • Ah... from your screenshot I see that your sidewalks are segmented by block (naturally). If your roads are also my suggestion should work. Otherwise it will not. – Russell at ISC Sep 06 '13 at 15:19
  • The sidewalk is not segmented in the same way as the road. Thanks for your help anyway – 12B01 Sep 06 '13 at 16:49
  • If you are a programmer you could write code to detect which side the sidewalks are on by intersecting perpendiculars from a sidewalk to the road to see where along the road the sidewalk is, then from that part of the road to the sidewalk to see which side it's on. That way you could identify sections of road with sidewalk on only one side. But I don't know of a tool to do this for you. – Russell at ISC Sep 12 '13 at 13:36