Vulnerability: A Model-Based Case Study of the Road Network in Stockholm

Abstract

Vulnerability, exposure and criticality in various infrastructures are issues that have been more explicitly looked into in recent years. However, road vulnerability as such has not been in focus for very long, despite the fundamental importance of our road networks in everyday life, as well as in crisis evacuation situations. Consequently, network reliability in transport modelling is an important and growing field of research (Lam 1999). The connection between reliability, vulnerability and other related concepts are discussed in Berdica (2002), with the main proposition that vulnerability analysis of road networks should be regarded as an overall framework, within which different transport studies can be performed to describe how well our transport systems function when exposed to different kinds of disturbances. Following that approach, this paper presents the results from a model-based case study, performed with the overall objective to study how vulnerable the Stockholm road network is in different respects. More specifically it is built up around three main questions:

• 1. How do interruptions of different critical links affect the system and how important are these links in relation to one another?

• 2. How is the network performance affected by general capacity reductions and possible prioritisation of a sub-network?

• 3. How is the system affected by traffic demand variations, i.e. how close to its capacity limit does the system operate?