Time impedance does not honor default cutoff value correctly

KimVoros1 — Thu, 14 Mar 2013 01:03:53 GMT

I've created a network data set to that utilizes hierarchy to assign and global turn delay to assign a severe penalty to crossing unsignalized arterial roadway crossings. The intent was to assign a high value and set the cutoff value well below the threshold. In testing the network, I've determined that cost is accumulating as expected, but network analyst is finding routes with a much higher cost value than I've specified in the analysis settings. I should note that I used the Global Turn Delay calculator to set my turn delay very high for local roadways crossing arterials.

Network analyst will not 'solve' when the cutoff is lower than 150. However, when I use any higher value the time accumulation is well above the threshold (about 5,000) which is the value I assigned to the intersections. Coincidentally, the points are about 150 M apart. I'm wondering if I've set the evaluators incorrectly? Screenshot attached.

Re: Time impedance does not honor default cutoff value correctly

PatrickStevens — Thu, 14 Mar 2013 18:56:03 GMT

You have found a bug! There should a prize or something for you, but all I can give is my gratitude. Strangely, even though this bug has been around since 10.0, it has gone unnoticed until you and one other user both found it this week.

The problem is that the Global Turn Delay Evaluator is being ignored when the route is being calculated. The delay cost is added in when the total cost is given in the results, but during the search, it is not considered. We have a bug entered for this and it will be fixed in the next release.

That means, unfortunately, that you won't be able to use the GTDE in the way you were trying to. You'll need a workaround. How many places do you have unsignalized arterial roadway crossings? If it is not too cumbersome, you could digitize in turn features with turn delay costs. Or you could place additive point barriers with the correct curb approach to ensure that travel in the right direction off of an edge picks up the cost.

Look into these solutions, or ask more questions and I'll help you figure out a way to accomplish your goals without using the GTDE.

Sorry for the inconvenience, but thanks for helping us improve the software.

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Time impedance does not honor default cutoff value correctly

Re: Time impedance does not honor default cutoff value correctly