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