Hi,You will need the two-dimension capacity in routes: one for regular seats and the other one for wheel chairs. There is no need to introduce specialty for wheel chair. The following python code can help you to load the capacities into routes. Just open the layer in ArcMap and type in the following code in the python window (make sure to modify the layer name "MyVRPLayer" and route name "route 1, route 2, ..." accordingly).
routeCapacity = {'route 1': '12 0', 'route 2': '11 1', 'route 3': '11 2', 'route 4':'9 3', 'route 5': '6 4' }
rows = arcpy.UpdateCursor("MyVRPLayer\Routes")
for row in rows:
row.Capacities = routeCapacity[row.Name]
rows.updateRow(row)
del row
del rows
Hope this answers your question.Thanks.Anna