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The city of Stockholm has a goal of reducing traffic work within the municipality by the year 2030. To achieve this, a change in the travel pattern will be required for Stockholm County in its entirety. The population has increased in all municipalities in Stockholm County and that increase is expected to continue. In recent years, traffic work has decreased per capita but increased overall. This indicates that countermeasures are required to reduce the amount of traffic work. This study aims to investigate whether a reduction in the capacity of the Central Bridge can lead to a reduction in traffic.According to studies globally, a reduction in capacity leads to reduced traffic work rather than the system breaking down. Important lessons in avoiding system breakdown are that the road network is robust and that there are alternative means of transport. In this study, the Swedish Transport Administration's base forecast for the year 2040 has been used together with a compilation of similar projects globally and lessons learned from them. According to the base forecast, the traffic work is estimated to increase until 2040. If the Central Bridge has a reduced capacity, it leads to a one percentage point reduction in traffic work in the municipality of Stockholm per reduced lane. This further leads to better air quality in the inner city as traffic work moves out into the rest of the municipality and county.The study has used Sampers, the demand model that handles the Swedish Transport Administration's basic forecasts, to analyse various aspects of the transport system. Despite its usefulness, the model has some limitations such as the separation of the public transport road network and the car road network, where congestion is only considered for car traffic. This shortcoming means that the effects of a change in congestion do not affect public transport journey times. The model is good at identifying the impact of a change in the road network on vehicle traffic but has more difficulty in identifying transfers between transport modes. Nevertheless, the model gives some indication of a shift to more sustainable modes of transport such as public transport, walking and cycling. It also gives an indication of more local car travel as transport costs increase for trips to and from Stockholm city centre for motorists. Over both the Customs section and the Saltsjö-Mälar section, the share of public transport increases.

This thesis proposes an analysing tool that makes use of route set generation to perform road network analysis that can be used in both transport planning and traffic management analysis. The input to the tool is a routable road network and a geographical zoning system and the route set generation is performed on all Origin-Destination (OD) -pairs of the zoning system. The tool was implemented using a simplification of Stockholms road network and a zoning system defined by the Swedish Transport Administration. The result shows that a route set generation-based tool can provide support in both transport planning and traffic management, and that the procedure provides results within a reasonable amount of time. The tool provides both a general analysis of the road network, and a link capacity reduction analysis. In the latter, the proportion of affected destinations and mean travel time deterioration for each OD-zone work as metrics of how the zones are affected by the capacity reduction. Transport planners can use the tool to present the betweenness centrality, the proportion of affected destinations and the mean travel time deterioration, all of which are metrics that can be used to evaluate the potential need for new infrastructure. Traffic managers can use the proportion of affected destinations and the mean travel time deterioration as metrics that can be used to identify zones that are affected by a road capacity reduction. The betweenness centrality of the best alternative route can be used to support traffic diversion for a specific zone.