9. Visualization of accessibility map
Accessibility Calculator accomplishes every scenario with the thematic map(s) of the major results. In the case of the Service area maps, these are maps of the travel time. In the case of the Region maps, these are maps of the chosen aggregate measures.
9.1. The style of presentation
The default map style is Graduated, with the [Minimum accessibility, Maximal accessibility] interval is split into bins as follows:
Service area maps – the interval [0, Maximum travel time] is split into constant 5-minute bins.
Region maps – the interval is split into the Number of bins that was set when the maps were calculated. This parameter is read form the log file of the compared scenarios.
Compare accessibility maps – the [MIN, MAX] interval of the measure is divided into deciles.
The palettes for the visualization are supplied with the Accessibility Calculator plugin and use in in the examples of this and other sections. The Accessibility Calculator presents a thematic map only and to make a proper map, the user must design and apply a QGIS layout. We recommend designing this layout in advance in order be always ready to present the map outside.
9.2. Layers for visualization
The results can be visualized based on:
The layer of buildings (not recommended)
The layer of the Voronoi polygons that are constructed based on the buildings’ centroids.
The layers hexagonal cells. The standard layers that are suggested are the layers of hexagons with the side of 50, 100, 200, 400, and 800 m. The user can choose to build some of these layers only or construct the layer of hexagons with different side length. There is no need to build all layers in advance, the hexagon layers can be constructed at any stage of plugin use.
The layers of the Voronoi polygons and four hexagon layers are built at the Data preprocessing → Build visualization layers stage. The IDs of the visualization polygons must repeat the IDs of the buildings, and each polygon will present the results for the building with this ID. The maps below (Figure 1) present the results of the same computations based on the Voronoi polygons of buildings, and the hexagons with the side of 100, 200 and 400 m.
a
b
c
d
Figure 1. Gesher Theater in Yafo from-accessibility at 22:30, after the performance is finished. Calculated with the Transit accessibility → Service area maps → From service locations - Fixed-time departure option. Visualized with the Voronoi polygons of buildings (a), and 100m (b), 200m (c), 400m (d) hexagons.
9.3. Visualization of accessibility maps comparison
The map in Figure 2 presents the region accessibility map for Tel Aviv city computed based on the 200m hexagons that cover the buildup areas of the city:
Figure 2. Transit accessibility → Region maps → From every location – Fixed time departure accessibility map presents the number of buildings accessible in 45 minutes from each of Tel Aviv buildings with the transit network of 2024 that includes the Red LRT line
Figure 3 presents the comparison between two to-accessibility scenarios of the Yafo Gesher Theater at the beginning of the performance, 20:00. One of them is computed before and the other after the Red LRT line was established in the Tel Aviv Metropolitan Area in 2024. After the Red LRT line was established, accessibility to the distant buildings along the northeast part of the LRT line increased, while accessibility to the buildings to the south and west of the LRT line decreased (Figure 3a) due to the cancellation of several bus lines. At the same time, The Gesher Theater became accessible in less than 45 minutes from many additional buildings after the Red LRT line was established, while the number of buildings from which is became non-accessible due to the cancellation of the bus lines after the LRT line started functioning are few (Figure 3b).
Figure 3. The output of the Compare accessibility maps → Service Areas comparison between two to-accessibility transit maps of the Gesher Theater in Yaffo before and after the Red LRT line was established. The difference between the two maps (a) and the map of buildings that are accessible in 45 minutes with one of the networks only (b). The layer of buildings’ Voronoi polygons is chosen for the visualization. The maximum travel time is 45 minutes
For more examples of visualization see here.