Join multiple unconnected lines for input into service area analysis

09-17-2016 05:01 PM
New Contributor

Hi, I'm doing a walkability analysis, and creating service areas around Census mesh blocks (centroids). My issue is that I have 4 line files; 1) roads network, 2) roads and tracks in national parks network, 3) cycleways and 4) footpaths and walkways. When I run SA using all 4 line features, the tool only uses the road network (1 & 2). I have checked this with generate lines, and also tried many different parameters when setting up the network and in the service area properties. 

I am aware why this is so; it is because both the cycling and walking network are not connected, and consist of multiple small unconnected line segments. I can eliminate the cycle network from the analysis, because much of it is on road anyway, and the digitising has been done very sloppily (mostly straight lines between points). 

However, I would like to use the walkway network, but am stumped how I can do this. What I would really like to do is some way of joining the segments together (these have obviously been digitised off aerial photos and in a park, for example, may have 10 small line segments instead of a single walkway) and snapping these (the endpoints) to the roads network. Otherwise my connectivity fails. 

Obviously I can edit this manually, but it is a very large area, and will take me days if not weeks. I have so far tried a) integrate, b) geometric network, c) establishing a topology, d) converting lines to points and back again to line, e) snapping. None of these are very effective. Topology is the most effective, but snapping the end points have to be done manually as I don't want all endpoints snapped. 

Ideally, I would like to join the segments together when off road (i.e. in a park) to create one path; and snap this to the road centreline. Or use something like the tools in the Add GTFS to Network, which creates connector lines. For the footpaths along the roads, I am happy just to add a field to my road table, and weight (more favourably) roads with footpaths over roads that don't have any. 

Would anyone have any idea how to do this without having to manually edit the line features? 

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New Contributor

Update: I have done a workaround for this. I selected all walkways within 10m of the roads, and exported this as another shapefile (Footpaths *sidewalks for US people*) and reversed the selection and exported the rest as Pathways. 

I then merged both files with the roads file, and updated the attributes so that I had the same fields (walk time, length in meters and km, etc, name and type of 'road'). I checked this against the aerial photo and original shapefiles, and these matched well.

After I merged the two files, I did a check and repair geometry and removed about 500 tiny segments of line. 

I then ran a series of SA using various locations (except for the mesh blocks one, as the 9000 odd facilities crashed the program) with generalized polygons, overlapping, no trim and line generation; and this worked perfectly, and used all types of 'road', including my pathways, to access the facilities. 

This was a very easy way of solving this problem, but may not be suitable for anaylses other than my specific problem. I'm mainly looking for the polygons to compare service areas against census data, landuse, density etc, as these are a more detailed method than using buffers. 

Anyone has any other solutions, I'm happy to try them and compare the result. I'd still like to get the walkways into a more usable dataset (without editing each segment). 

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