I have a road network downloaded from Ordnance Survey (Meridian 2, with A roads, B roads and Minor roads Merged into one shapefile and then built into a Network Dataset for use in ArcGIS' Network Analyst) and would like to use it to determine Service Areas for 4 hospitals (preferably with drive times of 30 minutes and 60 minutes) and Closest Facilities (same 4 hospitals and directions from 539 points).
I've used the Network Dataset to find the Service Area and the Closest Facility but the only parameter I can use is distance (metres).
Question: How do I set up the network to use drive time, not distance, and work out Service Area by, say, 30 minutes?
When I try to create the Network Dataset from the downloaded road network, I try to add Drive Time as an Attribute but I can't get the Network Dataset Wizard to accept the evaluators.
I've tried to follow the ESRI help pages and I've Googled around but I'm lost. I'm not sure what the time setup should be or if it's something I can just do or something I need to set up from the start.