Make Route with Python and Network Analyst in ArcGIS Desktop giving ERROR 000192

Question

I'm having trouble debugging my python code to create a network analyst layer in ArcGIS 10.0. Basically when run from a script tool the code completes successfully without actually doing anything or returning any sort of useful information, and when run from the embedded python window in ArcGIS 10.0 i get the following error.

"Runtime error <class 'arcgisscripting.ExecuteError'>: Failed to execute. Parameters are not valid. ERROR 000192: Invalid value for Time Attribute Failed to execute (MakeVehicleRoutingProblemLayer)."

The script is supposed to solve the route and create a layer file for the output Here is my code below:

#Import system modules
import arcpy
from arcpy import env

try:
    #Check out the Network Analyst extension license
    arcpy.CheckOutExtension("Network")

    #Set environment settings
    env.workspace = r'C:\Layout3.gdb'
    env.overwriteOutput = True

    #Set local variables
    inNetworkDataset = r'C:\Layout3.gdb\NtsFDS\NtsFDS_ND'
    outNALayerName = "TestResult"
    
    impedanceAttribute = "CABLE_COST"
    distanceAttribute = "TRAVEL_TIME"
    timeUntis = "Minutes"
    distanceUntis = "Meters"
    inOrders = r'\Layout3.gdb\NtsFDS\Orders'
    inDepots = r'C:\Layout3.gdb\NtsFDS\Depots'
    inRoutes = r'C:\Layout3.gdb\NtsFDS\Route'
    outLayerFile = env.workspace + outNALayerName + ".lyr"
        
    outNALayer = arcpy.na.MakeVehicleRoutingProblemLayer(inNetworkDataset, outNALayerName,
                                                         impedanceAttribute,
                                                         distanceAttribute)
    
    outNALayer = outNALayer.getOutput(0)

   
    subLayerNames = arcpy.na.GetNAClassNames(outNALayer)
    
    ordersLayerName = subLayerNames["Orders"]
    depotsLayerName = subLayerNames["Depots"]
    routesLayerName = subLayerNames["Routes"]
        
    candidateFields = arcpy.ListFields(inOrders)
    orderFieldMappings = arcpy.na.NAClassFieldMappings(outNALayer, ordersLayerName,
                                                       False, candidateFields)
    arcpy.na.AddLocations(outNALayer, ordersLayerName, inOrders, orderFieldMappings,"")

    
    depotFieldMappings = arcpy.na.NAClassFieldMappings(outNALayer, depotsLayerName)
    arcpy.na.AddLocations(outNALayer, depotsLayerName, inDepots, depotFieldMappings, "")
    
    arcpy.na.AddLocations(outNALayer, routesLayerName, inRoutes, "", "")
    
    #Solve the VRP layer
    arcpy.na.Solve(outNALayer)
    
    #Save the solved VRP layer as a layer file on disk with relative paths
    arcpy.management.SaveToLayerFile(outNALayer,outLayerFile,"RELATIVE")
    
    print "Script completed successfully"

except Exception as e:
    # If an error occurred, print line number and error message
    import traceback, sys
    tb = sys.exc_info()[2]
    print "An error occured on line %i" % tb.tb_lineno
    print str(e)

Answer 1

For this code to run you will need to upgrade to ArcGIS Desktop 10.1 because the ArcPy Network Analyst module (arcpy.na) was only introduced at that release - see What's new for geoprocessing in ArcGIS 10.1.