Network evolution

Network indicators are widely used for characterizing  transport network topology and its performance as well as provide insights on possible developments. Public transport networks change dramatically over time and are have a significant impact on urban and regional development. The structure of transport networks is the outcome of a large number of infrastructure investment decisions taken over a long time span. Little is known however on how rail bound public transport networks and their network indicators have evolved into their current form as it is surprisingly difficult to obtain data on historical network states.

This study reports a longitudinal analysis of the topological evolution of a multimodal rail network by investigating the dynamics of its topology for the case of Stockholm in 1950-2025. The starting year marks the opening of the metro system while the end year is set to mark the completion of the current development plan.

In the link below you can get an impression of the network evolution with 5 years intervals. Note the changes in coverage (scale) and density.

https://www.dropbox.com/s/iklil4shu2wgd6b/Evolution.wmv?dl=0

Based on a compilation of network topology and service properties, a year-on-year analysis of changes in global network efficiency and directness as well as local nodal centrality were conducted.

Changes in network topology exhibit smooth long-term technological and spatial trends as well as the signature of top-down planning interventions. Stockholm rail network evolution is characterized by contraction and stagnation periods followed by network extensions and is currently undergoing a considerable densification, marking a shift from peripheral attachment to preferential attachment. It is remarkable that in 2025 the Stockholm network will offer the same level of directness, connectivity and accessibility that were offered in 1950 for a much smaller area. This is driven by the dramatic shift in the modal composition of Stockholm rail-bound network during the analysis period.

Read the full paper following this link.