Travel modes on a network dataset define how a pedestrian, car, truck, or other medium of transportation moves through the network. A travel mode can be general—for example, to model typical trucks—or more specific, such as to model ladder trucks or rescue trucks.
A travel mode is essentially a template consisting of a long list of travel settings that define the physical characteristics of a vehicle or pedestrian. Those characteristics are considered when performing a network analysis to define how the vehicle or pedestrian travels and where it can go. Selecting a predefined travel mode allows you to efficiently and consistently set a number of properties that are appropriate for the mode of travel you intend to model. The benefits are time savings and reduced complexity—you don't need to remember and configure, with each analysis, the parameter values that most accurately characterize the vehicles you're modeling.
Example: Ladder and rescue trucks
A fire department frequently performs route analyses to find the quickest way for their vehicles to reach an incident. The vehicles vary in size and maneuverability. To compare ladder and rescue trucks, for instance, rescue trucks are faster than ladder trucks, so their travel times are shorter. Ladder trucks are taller and face more height restrictions, which can result in longer routes. Unlike rescue trucks, ladder trucks cannot make U-turns at intersections, which can exclude time-saving opportunities.
Whenever dispatchers solve a route analysis for a ladder or rescue truck without using travel modes, they need to set various analysis properties to appropriately model the truck they're routing. They do this by choosing an impedance value to model the travel time, setting values for height restrictions and U-turn policies, and defining several other vehicle-specific properties.
Setting these parameters at the time of analysis is avoided, however, by using travel modes. The fire department creates two travel modes on the network dataset: Ladder Truck and Rescue Truck. Each mode is assigned values for the vehicle-specific travel parameters. When dispatchers need to generate a route for a ladder truck, they set a travel-mode parameter on the analysis to Ladder Truck and skip the process of explicitly setting properties for the vehicle's impedance, vehicle height, U-turn policy, and so on. Instead of setting several parameters with each route analysis, they set one.
This section lists the settings defined by a travel mode. It also provides examples of how these values may differ between travel modes.
Name—The unique name of the travel mode. Blank names or names containing < or > are not allowed.
You can perform the following by clicking the Options button in the upper right corner of the dialog box.
- New (Ctrl+N)—Create a new travel mode.
- Copy (Ctrl+Shift+N)—Create a copy of an existing travel mode.
- Delete (Ctrl+Shift+D)—Delete an existing travel mode.
- Rename (F2)—Rename a travel mode.
- Make Default (Ctrl+H)—Set an existing or newly created travel mode as default.
Description—A short description of the travel mode.
Type—Indicates the category of travel or vehicle represented by the travel mode.
Travel modes are grouped into broad categories using the Type setting. For example, a logistics company might have several travel modes representing different sizes of trucks, but each of these modes falls under the Truck travel mode type. Applications and tools that use travel modes may use Type to optimize behavior or settings.
Impedance—Specifies the cost attribute on which to optimize the analysis.
A travel mode modeling cars would need a cost attribute that stores the time it takes a car to traverse an edge or street segment. In contrast, a Walking Time travel mode would need a cost attribute storing the time it takes to walk along edges or streets. A distance-based cost attribute, such as Meters, can be used for either a Driving Distance or Walking Distance travel mode.
Time Attribute—Specifies the time-based cost attribute for reporting directions.
The choices for Impedance and Time Attribute are typically the same when modeling time-based travel modes. When modeling distance-based travel modes, however, the Time Attribute value would need to describe how long it takes the travel mode to travel along network edges. For a Walking Distance travel mode, for instance, Time Attribute would be set to a cost attribute storing walking times.
Distance Attribute—Specifies the distance-based cost attribute for reporting directions and for solving vehicle routing problems.
Driving Time and Walking Time travel modes would need Distance Attribute set to a distance-based cost attribute, such as Meters.
Restrictions—Indicates the restriction attributes that are respected during solve time.
A Trucking Time - Corrosive travel mode may set several restrictions to require trucks to follow designated truck routes when possible, avoid roads where corrosive-materials cargo is prohibited, and so on. Walking modes often have restrictions set that prohibit highways where pedestrians are not allowed. Furthermore, wheelchair travel modes restrict stairs.
Parameter Values—Specifies the parameter values for network attributes that have parameters.
A Trucking Time travel mode can set a Vehicle Height parameter to prevent the vehicle from going under bridges where that type of truck won't fit. For a Walking Time travel mode, walking speed is often set as parameter.
U-Turns—Indicates where the travel mode is allowed to make U-turns.
A travel mode that models trucking time would likely have U-Turns set to Not Allowed. Yet, Walking Distance would have it set to Allowed, since pedestrians can easily turn around anywhere.
Use Hierarchy—Indicates whether the travel mode uses the network hierarchy in an analysis.
Driving travel modes use hierarchy, but walking modes don't; drivers tend to be more willing to travel farther to avoid complicated routes that have more turns and stops. Pedestrians tend to prefer shorter distances, even if the route is more complex.
Simplify Output Geometry—Specifies whether the travel mode generalizes the geometry of analysis results and by how much.
Larger simplification values result in reduced bandwidth requirements and rendering times, but the output line and polygon features aren't as clear, especially as you zoom in on the map. Output routes for walking modes are not simplified as much as they are for driving modes. Pedestrian routes are viewed at larger map scales, so more detail is needed for the route lines.
Use travel modes
When you create a new Network Analysis layer referencing a portal network analysis service or a local or enterprise network dataset, the new layer will use the default travel mode of the associated network dataset or service. Shapefile networks do not support travel modes, so Network Analysis layers referencing shapefile network datasets will use the default settings of the network. If you create the layer using one of the Network Analyst geoprocessing tools, you can choose which travel mode the layer should use.
You can view or change the Network Analysis layer's travel mode property on the Network Analyst layer ribbon.
The travel mode is actually a collection of detailed settings. To view or change the detailed settings of the current travel mode, such as the impedance attribute or restrictions, click the launcher button in the Travel Settings group, or right-click a Network Analysis layer in the Contents pane and choose Properties. The Travel Mode page of the Layer Properties dialog box appears.
Controls are available to change all the travel mode settings. To change parameter values, expand the Restrictions and Parameters section and click the row with the attribute and parameter you want to change. The parameter details appear, allowing you to edit individual parameter values.
Changing any of the travel mode settings and clicking OK gives you a custom travel mode specific to that layer. The custom travel mode is no longer associated with the travel mode on the network data source and is not available for use with other Network Analysis layers. You can tell that your travel mode is custom by the angle brackets (<>) that enclose the mode name on the ribbon.