A company was faced with the decision to either open a new branch in Bamberg or Coburg and asked Geofabrik to back the decision with information about the reachability of these two cities by car and the number of inhabitants in the area around these two cities. They wanted to know
To answer these questions, reachability polygons were computed using Geofabrik Spider Graph for both Coburg and Bamberg. The rings (10 minute interval) around both cities were merged in order to see which regions are more than n minutes aways from any of the cities. By intersecting the polygons, it was determined which areas have an almost equal distance to both cities. The results can be seen in the following map.
Select overlay:
To answer the questions which involve population data, the dataset Bevölkerung im 100 Meter-Gitter (population in a 100 meter grid), a result of the 2011 European Union census in Germany, was used. The dataset is available as a CSV file under the Data Licence Germany Attribution Version 2.0. It was imported into a PostGIS database and intersected with the polygons. The intersection resulted in the following table:
| Destination | Travel time (minutes) | inhabitants | sum |
|---|---|---|---|
| Bamberg | 10 | 92 199 | 92 199 |
| Bamberg | 20 | 103 056 | 192 255 |
| Bamberg | 30 | 141 560 | 336 815 |
| Bamberg | 40 | 792 125 | 1 128 940 |
| Bamberg | 50 | 704 351 | 1 833 291 |
| Bamberg | 60 | 320 481 | 2 153 772 |
| Coburg | 10 | 52 730 | 52 730 |
| Coburg | 20 | 56 360 | 109 090 |
| Coburg | 30 | 126 854 | 235 944 |
| Coburg | 40 | 228 382 | 464 326 |
| Coburg | 50 | 256 347 | 720 673 |
| Coburg | 60 | 174 439 | 895 112 |
