Merge overlapping lines in ArcGIS

Question

I have a polyline shapefile containing a number of lines, some of which overlap. By overlap, I mean that they follow exactly the same path for some of their route, but also have bits that are not shared. As it's difficult to explain in words, the following images should help:

In the example above, you can see how the two selected lines overlap, and I want to merge them into one line feature.

Is there a way to do this with a built-in ArcGIS tool? If not, is there an easy way to check for overlapping in Python? (and then an easy way to merge two lines in python?)

Answer 1

Dissolve Lines

update link (28th October 2014) http://resources.arcgis.com/en/help/main/10.2/index.html#//00170000005n000000 Single Part & DISSOLVE_LINES enable in the geoprocessing tool.

Answer 2

If you use an ArcEditor license you could start ArcCatalog and:

1. make a personal Geodatabase.
2. create a Feature Dataset in the Geodatabase.
3. Import your Shapefile in the Feature Dataset.
4. Create a Topology in the Feature Dataset.
5. Set the Topology Rule "Must not overlap" for your Layer.
6. Run the Topology Validation.
7. Check the results in ArcMap - you need to add the Topology Error Layer.

This will markup all the overlapping lines.

Hope this helps you :-)

Answer 3

To fix, turn on the Topology toolbar, start editing mode, and use the Error Inspector and Fix Topology Error Tool. There are other tools to help you on the toolbar as well.

Answer 4

In an editing session, you could select the line segments you want to merge, then select Merge from the Editor drop down menu. The dialog box that will pop up asks you which segment you want to merge the others into. Either select the segment you want, or if it doesn't matter just go with the default.

Answer 5

This function will remove overlapping lines and replace (not merge) each segment with one of the features:

def remove_overlapping(input_polyline, output_polyline, tolerance=0):
    """Identifies overlapping (portions of) of a polyline feature class and replaces with one feature."""

    overlapping_segments = ScratchPath + "\\Scratch.gdb\\overlapping_segments"
    # Tolerance defines "overlap."
    tolerance_expression = str(tolerance) + " Feet"
    # Cutout overlap portions.
    arcpy.Intersect_analysis(in_features=input_polyline, out_feature_class=overlapping_segments, join_attributes="ALL",cluster_tolerance=tolerance_expression,output_type="LINE")
    # Discard all but one feature.
    arcpy.DeleteIdentical_management(overlapping_segments, fields="Shape",xy_tolerance=tolerance_expression,z_tolerance="0")
    multipart_after_erase = ScratchPath + "\\Scratch.gdb\\multipart_after_erase"
    arcpy.Erase_analysis(input_polyline, overlapping_segments,multipart_after_erase, cluster_tolerance=tolerance_expression)
    # Break apart multipart features which might have been created when using erase.
    arcpy.MultipartToSinglepart_management(multipart_after_erase, output_polyline)
    # Put the remaining feature (after DeleteIdentical) back into the rest of the feature class.
    arcpy.Append_management(inputs=overlapping_segments, target=output_polyline, schema_type="NO_TEST", field_mapping="#")