## 3 OSM Street Network Evolution
### User Activity and Data Development
Thus, the various different street categories, which can also be found on the OSM Map Features web page (http:/wiki.openstreetmap.org/wiki/Map_Features), have been divided into four groups for the sake of clarity and for enhanced research and comparison methods; namely, motorways/dual carriageway, district/municipal roads, roads to/in residential areas, and other roads such as service roads and dirt/forest trails (Figure 4). Tracing the growth of the different categories, it can be noted that from a specific point in time, most categories do not expand any further. This indicates which category should be close to \"completion\" or in which category there are still new streets being added. It needs to be noted though that for comparison the TomTom dataset is suitable only for street network data for car-specific navigation, three out of the four categories. The \"other routes\" category can be compared only to  
Figure 3: (**a**) Increase in German OSM Street Network (three-month interval); (**b**) Annual Increase in German OSM Street Network (2007–2011). TomTom to a certain degree. In this fourth category, OSM has a far higher street network than the commercial provider. Based on the presumptions stated above and the comparison with the corresponding TomTom category street lengths, we reached the following conclusions. First, motorways and expressways were completely recorded for Germany by the middle of 2008. Second, all municipal roads for all of Germany were recorded by the middle of 2009. Third, streets that are close to or within residential areas are not fully recorded yet. Fourth, at the end of 2009 there were more segments in the \"other routes\" class in OSM than in the total TomTom commercial dataset. Fifth, in the middle of 2010 OSM surpassed TomTom in the total number of streets recorded. However, a high number of field and forest trails caused this advantage for OSM. Finally, most data contributions in 2011 are isolated street networks close to or within residential areas, but \"other route\" data, such as forest and field trails, are also increasing. The development of the individual categories in comparison to prior research results [32] and the commercial TomTom Multinet dataset from 2011 is depicted in Figure 5. The assumptions mentioned above with regard to the development and completeness of the total street network can here be confirmed too. Figure 4: Development of OSM Street Network in Germany by Street Category (2007–2011). Figure 5: Development of OSM Street Network in Comparison to TomTom. In June 2011, our studies for Germany showed that OSM had provided a street network for car navigation that is approximately 9% smaller than that of TomTom (Table 1). However, OSM's total street network is approximately 27% larger in comparison with TomTom's. In terms of pedestrian-related data and information, the OSM Germany dataset is even approximately 31% larger. In addition to the relative geometric completeness in comparison with another dataset, the internal completeness within the street network with regard to the street names is also important. This factor, sometimes also referred to as attribute accuracy [30], plays a significant role in applications such as routing applications that are being built on the specific dataset. Our results showed that a total of approximately 16% of streets in OSM have neither a name nor a route number (e.g., A 61) that could be used for car navigation. However, these results vary by street type in significant ways (Figure 6). The results clearly show that the majority of the unnamed streets are streets that are either within or close to residential areas. The \"unclassified\" street category could lead to confusion in this case, since streets that have a linking function between villages are included within this category. Another reason for this high value could be the fact that many of these particular routes (e.g., country lanes) have been digitized from satellite images, thus the local knowledge to add the specific name of each route is missing.