Road Matching

[BenjaminBigelow]

Hello,
My question concerns the relationship between two line feature classes.  One of the line classes purely represents streets and highways.  The other line class represents and contains traffic flow data for these road segments.  However, this second class is offset and does not match up neatly with the geographically correct line class.  My question is this: what is the simplest way to match them up on a large scale?  Would it be easier to make a topology or perhaps use Python to scan and shift the traffic flow lines?  I'm a relatively new user of ArcGIS.  Thank you.

[JohnSobetzer]

If the differences are quite small, you could use the Integrate tool giving your roads layer the priority, and using a tolerance  large enough to fix all or most differences without unwanted changes.  You might have to test some different tolerances, and then manually clean up areas where the tolerance wasn't large enough.  Use copies since this changes the inputs, and while it should only change your traffic flow line that might not always be the case.

Alternately, you could do something similar by creating a geodatabase topology with rules requiring each layer to match and giving priority to your roads lines, and running a validation with a tolerance that works.  Again, I suggest using copies especially if you run the validation outside an edit session since you can't then undo the results.

Another option if you have the paid version of ETGeowizards is to do a global snap of polylines.

A different approach would be to use a copy of your road lines and attempt to transfer the attributes of your traffic flow to it, and then use it as your traffic flow dataset.  This might work better if the two lines are often outside any usable tolerances, but the different methods have their limits and will likely require cleanup afterwards.  See http://gis.stackexchange.com/questions/12575/how-do-i-correctly-perform-a-spatial-join-between-lines... for some ideas involving spatial joins, buffering and the near tool.

The foregoing can fix a lot of differences at one time.  If you only have a few to do to start with or as clean up, you can manually edit the flow lines to match the road via snapping, reshaping or using a mix of copying and pasting line sections from your roads layer into your traffic flow and deleting the replaced sections.  You will need to get your attributes transferred from the replaced line section to the new which you could do using the attribute transfer tool, or by merging the new with an existing line section that shares the same attributes.

[BenjaminBigelow]

Thank you for the suggestions!  I'm going to try them out and see what works best.