# Linear Referencing, identify the river mile intersection of the down stream line

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06-06-2013 12:45 PM
Occasional Contributor III
I have a feature class of topologically correct river features.  The line???s are single part features, they have the correct flow direction, and each line end is snapped to its downstream recipiant.

I have created routes using the linear referencing tools.  I exported the end nodes, and used the end node and the route to calculate river mile.  The trouble is...  In about half of the cases the distance along the line is zero because the linear referencing tools are getting a distance from the line that produced the end node.  What I want is to get the distance from the downstream intersecting line (which will be greater than zero!).  How do I accomplish this?

I have tried using the line work to linear reference using the routes, but this just returns a start distance of zero, and an to distance that is equal to the line distance and not the distance along the line it intersects.

Any help would be appreciated.
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MVP Honored Contributor
I have a feature class of topologically correct river features.  The line�??s are single part features, they have the correct flow direction, and each line end is snapped to its downstream recipiant.

I have created routes using the linear referencing tools.  I exported the end nodes, and used the end node and the route to calculate river mile.  The trouble is...  In about half of the cases the distance along the line is zero because the linear referencing tools are getting a distance from the line that produced the end node.  What I want is to get the distance from the downstream intersecting line (which will be greater than zero!).  How do I accomplish this?

I have tried using the line work to linear reference using the routes, but this just returns a start distance of zero, and an to distance that is equal to the line distance and not the distance along the line it intersects.

Any help would be appreciated.

I am not sure I am following your set up.  A picture would really help.  It sounds like you want to assign measures to fields and use them to rebuild the routes at branching points.  Is that correct?

Anyway, try getting a set of points at the Intersections using the Intersection Tool.  Then use the Locate Features Along Routes tool with the option to get all available routes to find the measure at the location of the intersection on the mainline route you want to follow.  To get the measure of the points use the Field Calculator with the Python expression of:

!Shape.Centroid.M!