Incident:

I would like to visualize transit accessibility using zone polygons

Resolution:

In transit, travellers’ choices are based on strategies. The optimal strategy is the one with the least expected impedance. Transit impedances are the sum of the perceived components: waiting time (at nodes), boarding and in-vehicle time and cost (at segments) and auxiliary transit time and cost (at links). Transit impedances are stored in full matrices.

Transit accessibility can be displayed using a Node polygon layer.

To display accessibility FROM a zone, create a destination matrix and save in it, for the zone of interest, the impedances stored in the full matrix. This can be achieved using the Matrix calculator Modeller tool with a calculation constraint by zone. For example:

Next, in a worksheet displaying the network, click the  button in the upper right corner of the worksheet and add a Node display -> Node polygon layer.

In the Node value field, select the recently created destination matrix. Browse for the shapefile containing the zone polygons and select the field containing the Node ID. Customize the Style legend according to your preferences, for example:

Accessibility to public transport would be shown as:

Save the worksheet (Save button in the upper right corner of the worksheet).