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Abstract:
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Traffic authorities often face the contest of solving the traffic problem as demand for mobility exceeds the available capacity of the transport network. Further investments in new roads can of course increase the system capacity. However, experiences from such attempts shows that the introduced capacity will be consumed quite rapidly, not to mention the fact that it also introduces new demand from car travellers, which results in even higher costs for the community, urban sprawl and accelerates the congestion problem toward higher level. As the cost for transport reaches a certain level, increased mobility as such can no longer be justified. Congestion pricing and few other restricting strategies can be adopted to resize the car traffic demand to a manageable level. In transport networks with remaining capacity on other modes than car, it is possible to encourage the car travellers to switch to other modes by influencing their trip cost. This is the basic idea with congestion pricing. The new trip cost, of course, motivates the traveller to reconsider his/her choice of mode, which if succeeded, reallocates mode shares and optimises the effectiveness of the transport system. Congestion pricing is an effective tool for managing urban traffic. This was apparent from the analyses carried out in association with the Stockholm Trial of congestion taxes and expanded public transport in 2006. The trial operated during a limited time period and it was thus not possible to gather sufficient data to analyse the long term impacts. Since August 2007 the congestion charging scheme has been made permanent and it now is possible to carry out such an analysis. The purpose of the research is to assess the spatial and temporal effects of congestion tax scheme on traffic. Analyses and comparisons are made between traffic before the 2006 Stockholm Trial, during the Trial, after the Trial and with the permanent congestion tax during autumn 2007.
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