Displaying isochrones and accessibility in PrT

With PrT, you have several possibilities to display the accessibility of network objects in the network:

With PrT isochrones, you can display the accessibility of each point in the network from one or several marked nodes, main nodes, or zones (Two-dimensional display of attribute values around point objects). Network objects can be origins or destinations of isochrone calculations. If the network objects are destinations, the isochrones specify the points from where the reference object can be reached within the same time.
You can display links according to their accessibility from currently marked nodes, main nodes, or zones (Setting the display for PrT isochrones at links).
You have the possibility to display nodes, main nodes, or zones classified according to their accessibility from currently marked network objects and use the Isochrones time PrT attribute for the classification (Displaying the accessibility of network object types according to classes).

Note: You can use all display types all at the same time.

1. If required, change the settings for isochrones in the Edit graphic parameters window (Setting graphic parameters for the display of isochrones).

2. On the Graphics menu, click Isochrones.

The Graphics tools (Isochrones) window opens.

3. Select the PrT tab.

4. Specify any further settings you need.

Element	Description
	Click this icon to delete the list of objects and all previously executed isochrones.
Network object type	Here you select the network object type from which you want to measure the distances. The following types are provided: Nodes Main nodes Zones
Transport system	Here you can select the transport system.
Route choice criterion	Here you can select the route choice criterion. The following criteria are provided: tCur Run time in the loaded network t0 Run time in the unloaded network Distance Link length Impedance Impedance according to the assignment parameters AddValue 1...3 Attributes with user-defined values
Search direction	Here you can specify the search direction of the isochrone. Network objects are origins If this option is selected, the isochrone displays the accessibility of each point in the network from the reference object. Network objects are destinations If this option is selected, the isochrone indicates the points from which the reference object can be reached within the same time.
Restrict search	Unlimited search If this option is selected, the route choice criterion is not limited. Cancel search when maximum value is reached If this option is selected, you can specify a maximum value for the route choice criterion selected. The shortest path search is canceled when this value is reached. This saves computing time. Maximum value Entry field for the maximum value of the route choice criterion. Notes This field is only available if the Cancel search when maximum value is reached option is selected.

5. Depending on the network object type selected, in the network click the desired node, main node or zone.

Tip: Alternatively, to select a network object, right-click in the network and search for the desired network object in the search window (Finding network objects in the network).

Note: If on the toolbar, the Click only active objects button is activated, you cannot use the mouse to select passive network objects (Marking only active network objects).

In the Graphics tools (Isochrones) window, in the Selected network objects section, a new row is displayed for the selected object.

Note: To edit the network object displayed, in the Selected network objects section, click the network object and in the search window, search for the desired network object (Finding network objects in the network).

6. If required, click further nodes, main nodes, or zones.

Notes: You can undo your selection by clicking a selected object again.

You can select network objects of different object types simultaneously. To achieve this, change the entry in the network object type drop-down list in the Graphics tools (Isochrones) window.

7. Click the Execute symbol .

The isochrones are displayed according to your settings.

Notes: In isochrone mode, you can use the functions from the Network editor window's toolbars without leaving the isochrone mode.

You can switch off the display by clicking the Initialize button.