Service area: setting impedance in model builder?

AZendel — Tue, 15 Apr 2025 15:33:35 GMT

The below is the ArcMap UI for setting impedance in a service area layer:

Is there a way to set this in model builder?

Our county's central GIS office set up our network dataset and I can't change it. It includes attributes (fields) such as FT_COST, FT_SPEED, FT_MINUTES. FT_COST and FT_MINUTES are the same for most street segment - they both represent time costs. I need service areas based on distance (feet or miles), but model builder seems to keep defaulting FT_COST or FT_MINUTES. If I change the impedance in Pro to "CostLength feet" in the above screenshot, I get the expected results. One way streets and overpasses (F_ZLEV, T_ZLEV) are respected as well.

But I want to use model builder so we don't have to go through all of these steps manually. But I can't find a place to set the impedance to distance/length. Is this possible in model builder?

I also tried exporting the model to python and then adding a travel mode:

#new_travel_mode = arcpy.na.TravelMode(travel_modes["Driving Distance"]) new_travel_mode = arcpy.na.TravelMode() new_travel_mode.impedance = "Feet" # Process: Make Service Area Analysis Layer (Make Service Area Analysis Layer) (na) Service_Area2 = arcpy.na.MakeServiceAreaAnalysisLayer(network_data_source=TRANSROUTING_ND, layer_name="Service Area2", travel_mode=new_travel_mode, travel_direction="FROM_FACILITIES", cutoffs=[2], time_of_day="", time_zone="LOCAL_TIME_AT_LOCATIONS", output_type="LINES", polygon_detail="STANDARD", geometry_at_overlaps="OVERLAP", geometry_at_cutoffs="RINGS", polygon_trim_distance="100 Meters", exclude_sources_from_polygon_generation=[], accumulate_attributes=["CostLength"], ignore_invalid_locations="HALT")[0]

But line 6 bugs out with this error: ERROR 030232: Invalid travel mode value: "The travel mode refers to an impedance attribute that does not exist.''

I am using Pro version 3.0.3. We can't upgrade due to incompatibilities with our county's ArcGIS Server Version.

Thanks for any insight that you can provide!

Re: Service area: setting impedance in model builder?

MelindaMorang — Tue, 15 Apr 2025 15:52:08 GMT

As you've discovered, there's no way to use a custom travel mode in a model. You can only use travel modes that are stored permanently on the network data source.

Your Python script isn't working because "Feet" isn't the name of one of the impedance attributes on the network. From your screenshot, it looks like the attribute is named "CostLength". The "Feet" you have highlighted in the screenshot is the unit of measurement used by the attribute. It's just there for informational purposes.

Here's the documentation for how to construct a custom travel mode object in Python: https://pro.arcgis.com/en/pro-app/latest/arcpy/network-analyst/travelmode-nax.htm

You're on the right track.

new_travel_mode = arcpy.na.TravelMode(travel_modes["Driving Distance"])
new_travel_mode.impedance = "CostLength"

If you're planning to use Python to automate your workflow, check out this page for a better alternative than using the MakeServiceAreaAnalysisLayer geoprocessing tool: https://pro.arcgis.com/en/pro-app/latest/arcpy/network-analyst/performing-network-analysis.htm

topic Service area: setting impedance in model builder? in ArcGIS Network Analyst Questions

Service area: setting impedance in model builder?

Re: Service area: setting impedance in model builder?