topic Re: How to avoid a U-Turn when Stop is set at a override? in ArcGIS Network Analyst Questions

How to avoid a U-Turn when Stop is set at a override?

LeoDeng — Thu, 05 Sep 2019 12:52:00 GMT

Hi All,

As the document mentioned, "Currently when a network location is on a junction, the ArcGIS Network Analyst extension allows U-turns there, even when its CurbApproach property is set to No U-Turns and the U-turns at Junctions property of the network analysis layer is set to Not Allowed."

My question is when the stop is set as a street override (As we don't know which direction is best for the crossroad), how to avoid a U-Turn in this scenario?

The U-Turn policy is "Allowed Only at DeadEnds".

Environment:

ArcGIS Desktop 10.6 with Network Analysis Extension

Thanks,

Leo

Re: How to avoid a U-Turn when Stop is set at a override?

JaySandhu — Thu, 05 Sep 2019 21:53:33 GMT

When a stop is located on a junction than the curb approach property does not make sense as you can not figure out which way is the left or right side of that location. This is documented here:

U-turn policies—Help | ArcGIS Desktop

You can see the caution note in the curb approach section:

And this also explains that the U-turn at junction property applies to junction that occur in between stops.

So a way to not get into this issue is to locate your stops only on edges and not on system or override junctions of a network dataset. You can control what network sources to locate on from the route analysis layer's properties or on the add locations tool.

Jay Sandhu

Re: How to avoid a U-Turn when Stop is set at a override?

LeoDeng — Fri, 06 Sep 2019 11:30:19 GMT

Hi Jay,

Thank you for your explanations.

Set the stop source as streets could avoid a U-Turn certainly, however is there any solution in network analysis to avoid U-Turn when the stop is set at the junction?

As you can see in the result, there is a U-Turn. We want to avoid the U-Turn in the results and also keep the stop at junction point. Since we don't know which direction for the stop in the crossroads is correct before the route analysis.

Image that there are lots of waypoints set in the junction, the vehicle will go through these crossroads. And we also not allowed U-Turns. How can we implement it in ArcMap?

Thanks,

Leo

Re: How to avoid a U-Turn when Stop is set at a override?

JaySandhu — Fri, 06 Sep 2019 16:24:49 GMT

>Set the stop source as streets could avoid a U-Turn certainly, however is there any solution in network analysis to avoid U-Turn when the stop is set at the junction?

As I explained in the previous e-mail, this is not possible.

>Image that there are lots of waypoints set in the junction, the vehicle will go through these crossroads. And we also not allowed U-Turns. How can we implement it in ArcMap?

Why do the waypoints need to be on junctions?

One way to implement this: Let's say you want to get a route from A to B to C and want to avoid a u-turn at B (to C). Solve a route from A to B. Then use the Copy Traversed Source Features tool to get a list of edges that make up that route. Get the last edge ID (or create a point from it). Now do a route from B to C but put a barrier on that last edge. Combine the results. And do note that you may not get a path from B to C if u-turn was the only option.

Jay Sandhu

Re: How to avoid a U-Turn when Stop is set at a override?

LeoDeng — Fri, 06 Sep 2019 17:38:51 GMT

Hi Jay,

> Why do the waypoints need to be on junctions?

As we don't know which position in the crossroads is the best choice for the route.

Put a barrier and combine the results could be a solution.

Thanks,

Leo