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I can't seem to find any evidence of this question, but I'm surprised by that, so pardon if this has been asked.

If one is mapping crime location reports, by XY coordinates to streets, to create "hot street" segments, how does ArcGIS handle intersections? Which street (the East/west or north/south) and/or which side of the street, gets counts of events at intersections?

Is there a default logic to this? Looking at my map some segments get both intersections, some get one, and they all go to east/west streets, not the perpendicular intersecting streets.

For the left/right (east/west) issue, where some segments get both intersections and some get one, my guess was it's based on a true north/south/east/west grid, and whether the intersection is to the east or west, but I can't figure out why the perpendicular streets don't seem to get intersection incidents.

Maybe a work around is having those counts be specific to the intersection and not to the line segment? But, I'm not sure how to do that.

Thanks for any help in understanding how the system apportions these counts.

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What method is being used to map the points? Is it heads up digizing, GPS, etc? ArcGIS doesn't really handle intersections, unless there is a point there. It will snap within a tolerance to the closest line or point. So, the first question is how are your points being created. The 2nd is what process do you want to use to assign points to lines? This is something that you have control over, using the Spatial join, with a near function, or within distance of, etc. Give an idea of your process so far, and where you want to end up. –  Get Spatial Jul 13 '12 at 2:18
    
Thanks for the response. We are mapping XY coordinates assigned by our CAD system. When people input intersection name (main st & broad street) it puts the point wherever the CAD system has XY-ed that intersection. My main question is, once we've done this, there doesn't seem to be a systematic reason for why some incidents at intersections count in the total for the street segment to the left or right of the intersection, and never are counted on the street segments running north/south. Just curious if anyone knows how the system is deciding which street segment and if it can be controlled –  Chris Fisher Jul 13 '12 at 13:15
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ArcGIS wouldn't be calulating hot street segments by intesection but by streetedges. Your intersection points would be read not as intersections but as locations within polygon edges for the purposes of calcuation, calculations not being performed by intersection as that would not be how the data could be handled as it would have to be generalized to all streets at the intersection and would be too broad a generalization. Specific crime location not based on intersection but by correct position and location along the correct side of the street would be a much better approach and would approximate the machine logic being employed. Wowever, if you proceed with your problem as described you could place points or each edge of each street, near the junction. and then the data would be read for each polygon street edge, approximately near the intersection. Seems pretty messy though. Maybe a better way of locating the crime point than by intersection would have been a better way.

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