How do I prevent turns at a junction in Network Analyst
I'm using Network Analyst to build a road network for finding haulage routes. Unfortunately the data I'm using was not designed for routing, so I'm having to manipulate it a fair bit to get what I want. One issue I'm yet to resolve is how to deal with turns at junctions that shouldn't exist. In the screenshot below, the junctions in the green circle are actually an overpass/underpass scenario. I know I can delete the vertices to stop a junction forming, but this is proving difficult to automate because in some instances the vertices are the start/end of lines and then a break forms in the lines.
Instead, I'm sure there's a way to prevent a turn occurring at a junction but I can't for the life of me figure out how it all works.
Do I need to create a Turn Feature Class? If so, can I just populate it with segments (like below) and somehow set that as restricted in the Network Properties?
Is there another way? (I wanted to delete the junctions after they were created through a spatial selection but it's not editable).
Thanks for the links. By the looks of it, there's no way of mass creating this type of data - it must all be done manually (not what I was looking for unfortunately). I was looking for a way to solve many overpasses turning onto the underpasses instead of taking the on/off ramps.
I did manage to come up with a solution though. I did a once off pass of the data identifying the overpass or underpass I didn't want turns to happen on, buffered the segments 5 metres into a polygon feature class (yellow features below), and in my network building process, use those polygons to spatially select any segments (wholly within) and create one line data source, and then repeat it selecting everything else (wholly within inverted) to create a 2nd line data source. Both of these line feature classes are then used to build the network, but the one containing the no-turn features within the polygons are set to an Endpoint policy in Group Connectivity, whilst the rest of the data has an Any Vertex policy. Where the datasets meet, turns occur (valid intersections or connections), but when crossing an over/underpass, turns won't happen.
