topic Re: Restricting turns based on angle. in ArcGIS Network Analyst Questions

Restricting turns based on angle.

GeorgePualwan — Mon, 07 Aug 2023 19:58:13 GMT

Hello,

Hoping to get some information/push in the right direction with a network analyst issue I'm working through.

I am just now learning the extension, but I wanted to know is it was possible to set up turn restrictions based solely on the angle of the turn from one edge feature to another?

For context, I'm trying to apply this to an existing railroad network dataset to prevent it from routing illegal turns.

What seems to be the closest I've gotten is creating a restriction attribute for the network dataset. From there applying various combinations of logic in the source and default value evaluators using the Turn.Angle element variables and functions. Side question - Does anyone know how the Angle function gets calculated?

This is using ArcMap 10.8.1

It looks like it should be possible, but also might require some more complex configuration between network attributes and evaluators. I feel like I have tried just about every combination of settings, but there are many parameters so I'm sure I'm missing something.

Any pointers would be much appreciated!

Re: Restricting turns based on angle.

MelindaMorang — Mon, 07 Aug 2023 22:01:08 GMT

You can do this using global turns.

ArcMap: https://desktop.arcgis.com/en/arcmap/latest/extensions/network-analyst/global-turns-about-global-turns.htm

ArcGIS Pro: https://pro.arcgis.com/en/pro-app/latest/help/analysis/networks/turn-category-evaluator.htm

(Please note that ArcMap is entering mature support in March of 2024, and you are highly encouraged to migrate to Pro.)

Re: Restricting turns based on angle.

GeorgePualwan — Tue, 08 Aug 2023 11:33:00 GMT

Thanks. Can the global turns be set to fully restrict turns though? I could only get it to add time delays to the specific turn angles.

Re: Restricting turns based on angle.

MelindaMorang — Wed, 09 Aug 2023 18:26:23 GMT

I think you're correct and this is not possible. However, if you put a really long delay time for each turn category you care about (for instance, all left turns), this would effectively restrict them.

Re: Restricting turns based on angle.

GeorgePualwan — Thu, 10 Aug 2023 11:22:54 GMT

Update: I was able to get this working by creating an empty turn feature class and then setting up a restriction attribute to prohibit turns within a certain angle range. I'm not entirely sure why the empty feature class was needed, but this seems to be working properly now.