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How can I find intersection point in a road network in one line shapefile?

I am using QGIS 2.18.

How can I get the intersection point shown in blue colour

enter image description here

2 Answers 2

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Ok, that's the steps you need to folow.

  1. First use Dissolve without any attribute on your road layer.
  2. Next on dissolve layer use "Multipart to single parts" tool.
  3. After that use "Line intersection" on output from previous step.

I am not sure if i translate it correctly because not i am using polish version of QGIS. You can find in Vector toolbox.

Line Intersections

After that just select same feature line twice without any unic fields.

Fill in

EDIT

Ok i see that Dissolve in Qgis is a bit different that Dissolve in ArcGIS. But to work around it i came up with this idea.

  1. First Save As.. your existing shape file to work on copy.
  2. Next edit copy feature, select all lines and merge them together using "Merge Selected Features" from Advance Digitizing Toolbar and save it.
  3. Then use "Multipart to single parts" tool.
  4. After that use "Line intersection" on output from previous step.

enter image description here

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  • Thanks For Your kind responce.But this 'line intersection tool' return all points,not the intersection point.I am working in a single shape file(Line). here is the result, i.stack.imgur.com/nzzTB.png. Feb 27, 2017 at 4:28
  • It look like your lines are splitted into smaller parts that's why your output return so many points. Try to first dissolve your shapefile without any attribution and after run line intersection again
    – Losbaltica
    Feb 27, 2017 at 6:37
  • I will run line intersection of dissolve layer or the parent layer.Plz reply. Feb 27, 2017 at 7:35
  • Ok i edited answer. You need to use multipart to single part tool and after that line intersection. That should create you intersection point whenever line intersect each other.
    – Losbaltica
    Feb 27, 2017 at 8:13
  • Same thing is happening.not getting the required result.Anyway thanks for your kind responce,Thank You Feb 27, 2017 at 8:42
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Do you have the spatial query plugin installed? If so, you can probably follow the instructions here to query what you need: http://www.qgistutorials.com/en/docs/performing_spatial_queries.html.

If you only want to find one intersection, just make sure you pay close attention to how they limit the selection to rivers in the example. The same principles should apply for your query.

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  • Thanks fr ur answer.But I am operating with only one layer(a road network) Feb 28, 2017 at 10:13
  • Couldn't you put one of the roads into a new layer for purposes of the query and limit the data compared in the query to the road with which it intersects?
    – Brian
    Feb 28, 2017 at 14:27
  • Actually its a single road network(polylines) having 2500 attributes. Mar 1, 2017 at 4:27

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