Network Analyst with OS ITN Data

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09-05-2014 03:46 AM
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New Contributor II

Hello

I have created a network using the UK's Ordnance Survey ITN Data which looks fine.  However, when I run a service area the results are less than expected.  I have set the default breaks as 30, 60, 90, 120, 150, 180 minutes.  The service area is calculated and the polygons displayed on the map.  The problem is that the maximum distance that can be travelled is not being calculated correctly. 

From knowledge and driving a particular route regularly I know that the maximum distance being shown for the 180 minutes is below that which can be actually achieved.  I have checked this on Google and the particular route is just over 2 hrs. (120 mins) and not 180 mins

Is there a way within network analyst to set the speeds for a particular class of road, i.e. motorway, A road, B Road, etc.

Thanks in advance

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Hi Andrew,

You need to add two new fields (one field containing either speed limits or average speed of the different road classes and a second field containing the calculation of your new speed). Add your new speed field  as a new attribute in the Network Dataset Properties. And finally use your new speed field as an impedance.

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