topic Re: u-turns in network analysis in ArcGIS Network Analyst Questions

u-turns in network analysis

PaulRoseman — Thu, 12 May 2011 18:13:09 GMT

I am having trouble with solving routes due to u-turn issues.

I have created a driving network and loaded in geocoded points on a route with Network Analyst. When I only allow u-turns at dead ends, the solve fails. When I allow u-turns at intersections and dead ends then the route works, but inappropriate u-turns are taken. I have already increased the time penalty for u-turns in the driving network, and specified no u-turns on the stops.

Thanks in advance

Re: u-turns in network analysis

JaySandhu — Fri, 13 May 2011 15:32:51 GMT

What inappropriate u-turns are taken when you have intersection/dead ends option selected?
Perhaps that may point to some connectivity issue in the network (or many restricted edges) that cause no route to be found when you choose the dead ends only option.

Jay Sandhu

Re: u-turns in network analysis

PaulRoseman — Tue, 17 May 2011 18:18:50 GMT

U-turns were committed on dead ends, and on intersections. They also occurred in the middle of some blocks. Some of the U-turns at intersections were not necessary, there were paths to get around the U-turns.

Re: u-turns in network analysis

JaySandhu — Tue, 17 May 2011 22:24:04 GMT

There has to be a reason why a u-turn is made. For example the connectivity may not exist even though it looks like some roads are connected. Or there can be one-way restrictions and curb approach properties set that would cause a path to go up a road and then make a u-turn.

Look at the places were these u-turns are happening and use the network identify tool (second icon from right on the NA toolbar) to examine the connectivity at that location.
Jay Sandhu