As can be seen in the WebGL visualisation of the GPS data collected by the OSM contributors in Heidelberg (reported earlier in this blog), the quantity of recorded GPS tracks along an OSM highway features depends on the feature class. It has already been found before that the GPS data is not equally distributed among the roads and can considerably vary for different feature classes. In our study region of Heidelberg we have now found that motorway, primary, secondary and tertiary road segments are almost completely covered by at least one corresponding GPS track, whereas for the feature classes residential, path, pedestrian and footway, there is also a large share of segments that is not covered by any of the collected GPS tracks. Likewise, the average number of corresponding tracks varies considerably:
| feature class | | covered segments | | avg. # of tracks |
|---|---|---|
| motorway | 99% | 98 |
| primary | 99% | 21 |
| secondary | 96% | 11 |
| cycleway | 91% | 10 |
| tertiary | 95% | 9 |
| path | 52% | 2 |
| residential | 58% | 2 |
| footway | 35% | 2 |
