Network Analyst - Global Turn Delay Evaluator

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04-22-2010 10:00 AM
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Hello,

I have a hierarchy set up in my network that follows the supported model (Primary Roads, Secondary Roads and Local Roads). In the Global Turn Delay Evaluator, I get 20 types of supported turns (i.e. - Right Turn Form Local to Local Road, Left Turn From Secondary To Local Road, etc.). However, I don't see any options for left and right turns that involve primary roads (i.e. - Left Turn From Primary to Secondary Road). Does anyone know why Primary Roads would be excluded from the list of available turns? Right now, all of my Primary roads are freeways and major highways (including the on and off ramps attached to those segments). Thanks in advance for your help!

Jeremy
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Hi Jeremy,

The 20 turn categories you see are the default turn categories.  To fully specify all combinations of:
"Turn to the <a> from a <b> type road to a <c> type road across a <d> type road" would require 4*3*3*4 = 144 turn categories, so we have only these 20 by default to keep it more manageable.  Also, we do not want to discourage the solver from selecting turns on or off of primary roads by penalizing them in relation to the many turns expected in local and secondary roads unless discouraged by higher relative global costs.

On the "Global Turn Delay Evaluator" dialog in catalog when editing the evaluator properties you can click the "Load From File..." button and load the xml file extracted from the attached zip file.  The attached zip file contains the xml file to load and a screenshot of the dialog taken after loading this file. To see all of the 144 turn categories make sure the "Only Show Turn Categories for Local Roads" checkbox on the dialog is unchecked.  If you have a hierarchy attribute defined on your network, these categories will be used.  Now you can type in your preferred delay seconds in the "Seconds" column of the category type list at the bottom of the Global Turn Delay Evaluator dialog.

The 144 combinations in the attached file are all permutations of:
turn direction(4) : straight, reverse, right, left
from road(3) : local, secondary, primary
to road(3): local, secondary, primary
cross road(4): none, local, secondary, primary

-Rich
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Hi Jeremy,

The 20 turn categories you see are the default turn categories.  To fully specify all combinations of:
"Turn to the <a> from a <b> type road to a <c> type road across a <d> type road" would require 4*3*3*4 = 144 turn categories, so we have only these 20 by default to keep it more manageable.  Also, we do not want to discourage the solver from selecting turns on or off of primary roads by penalizing them in relation to the many turns expected in local and secondary roads unless discouraged by higher relative global costs.

On the "Global Turn Delay Evaluator" dialog in catalog when editing the evaluator properties you can click the "Load From File..." button and load the following xml file:
"C:\Program Files\ArcGIS\Desktop10.0\NetworkAnalyst\NetworkConfiguration\AllNetworkGlobalTurnDelaySettings.xml"
if you installed ArcGIS at the default location.

To see all of the 144 turn categories make sure the "Only Show Turn Categories for Local Roads" checkbox on the dialog is unchecked.  If you have a hierarchy attribute defined on your network, these categories will be used.  Now you can type in your preferred delay seconds in the "Seconds" column of the category type list at the bottom of the Global Turn Delay Evaluator dialog.

The 144 combinations in the AllNetworkGlobalTurnDelaySettings.xml file are all permutations of:
turn direction(4) : straight, reverse, right, left
from road(3) : local, secondary, primary
to road(3): local, secondary, primary
cross road(4): none, local, secondary, primary

-Rich
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