Two indicators for the city of Zurich: stress-free connectivity and accessibility to public services are calculated for the city’s cycling network. First, a network of all streets and paths in the city was created, and all segments were enriched with attributes such as speed limits, parking density, average daily motorised traffic, etc. Based on these attributes, the “Level of Traffic Stress” (LTS) – the stress potential arising from these attributes – was calculated for each segment. The LTS is a method developed by Mekuria et al. (2012) in transport planning to assess the quality of the cycling network while prioritising the diverse needs of cyclists. The Master’s thesis analysed how the two indicators differ for various groups of cyclists. The findings revealed that the cycling network in Zurich is fragmented and often disconnected for the two LTS groups with the lowest stress tolerance. In a further step, the same indicators were calculated for two future cycling network models to quantify their impact.
Map: LTS Network of the City of Zurich. The map on the left shows all LTS levels, while the map on the right displays only LTS levels 1 and 2. Navigation: Compare the two maps by swiping, zoom with the + and – buttons at the top left, navigate with the left mouse button, and view the attributes of individual segments by clicking on them. (Source: Stressfreie Konnektivität & Zugänglichkeit im Velonetz).
Background
The bicycle is an environmentally friendly means of transport that requires little space, is relatively inexpensive, and also promotes physical activity. It has gained importance in urban traffic over recent decades. Cities in Sweden, France, Germany, and Denmark have shown that good cycling infrastructure in particular encourages people to commute by bike. However, planning suitable cycling infrastructure depends on many different factors: existing regulations, financial resources, public support, and the availability of space in urban areas. In addition, any project must always be connected to a broader network in order to be sucessful.
Connectivity describes how connected different points in the network are and how easily they can be reached. It is a measure of the degree or quality of the connections and can be determined in various ways. There is no universally accepted definition of connectivity.
Accessibility refers to the ability to reach a desired destination. Traditionally, this has mainly meant time and distance. For cyclists, however, safety, comfort, and attractiveness are equally important. Therefore, the stress potential for cycling connections (Bicycle Level of Traffic Stress, LTS) as defined by Geller (2009) was used to assess accessibility. LTS divides people who actively cycle or are interested in cycling into four groups and determines, for each element in the network, which LTS group it is suitable for. This results in a network for each group.
The concept has so far mainly been used for cities in North America. To adapt it to the conditions in Zurich, the city’s Civil Engineering Office and the Pro Velo Zurich association were involved. The analysis and results were coordinated and discussed with both institutions.
Data, Methods and Resolution
As input for the indicators of connectivity and accessibility, the following data were used: the road network of the city of Zurich as a base, along with additional datasets containing information on cycling infrastructure, road width, speed limits, pedestrian islands, car parking spaces, average daily motorised traffic, one-way or two-way streets, tram tracks, pedestrian islands, and an elevation model. The datasets mainly originate from the city of Zurich or the Federal Office for Spatial Development. In the first step, the road network was enriched with these attributes.
Subsequently, the individual segments were assigned an LTS group, which were developed in collaboration with the Civil Engineering Office and Pro Velo Zurich. This resulted in a cycle network for each LTS group, for which the two indicators—connectivity and accessibility—were calculated. For connectivity, the shortest path within each LTS network between two random points within a defined radius was computed and compared with the shortest path in the overall network (without LTS restrictions). If a connection was possible within the respective network that did not exceed the stress level of the LTS group more than once and did not represent a significant detour compared to the shortest path, this path was considered ‘connected’. This procedure was repeated 10,000 times for each iteration of the various networks to ensure full coverage.
Accessibility is an extension of connectivity. Instead of using random points in the network, it starts from a building in Zurich and calculates routes to a public facility within a defined radius, such as a school, hospital, bank, or supermarket. The subsequent procedure is the same as for connectivity.
Availability and Publication of the Data
Connectivity and accessibility were calculated based on current data (as of September 2023). They have not been updated since. The indicators can be recalculated if the input data are updated.
Data Sources and Links
- Open Data of the City of Zurich
- Low-Stress Connectivity and Accessibility in the Cycling Network, ArcGIS-Storymap (in German) by Tim Fässler
- Low-Stress Connectivity and Accessibility; ‚Leave no one behind‘ in the Bicycle Network in the City of Zurich, Master's Thesis by Tim Fässler
- Mekuria, M. C., Furth, P. G., and Nixon, H. (2012). «Low-stress bicycling and network Connectivity». Mineta Transportation Institute.
Outlook
It would be worth to validate the classification schemes and the resulting classified road segments against the subjective perceptions of cyclists from different LTS groups, to ensure that the absolute values of the derived indicators are as realistic as possible.
The methodology and indicators allow for a wide range of extensions to assess the impact of specific transport planning measures on different groups of cyclists.
Bemerkung
For his Master’s thesis, Tim Fässler received the City of Zurich’s Traffic Safety Award on 6 November 2025.