Modelling effects of policy instruments for sustainable urban transport in Scandinavia

The purpose of this paper is to review the modelling used for the planning of infrastructure and design of policy instruments for transport in cities in Scandinavia, and to survey elasticities of transport demand with respect to policy instruments and important background variables. There are a number important objectives governing policy, maximizing welfare, reducing CO2 and other emissions, curbing congestion on roads and crowding in public transport in cities and improving the conditions for walking and cycling. The current transport demand models in Sweden and Norway were originally built to serve the purpose of forecasting for national infrastructure planning, primarily outside cities. They were not designed to represent the adaption of car use, congestion on roads or crowding in public transport or the effects of improving of conditions for walking and cycling. Therefore, recent discussions on the needs to develop planning for cities has raised these issues. The central results from the survey of effects are that, car use is shown to be more price sensitive in urban than in rural areas, and larger the larger the city. Although the benefits of a given congestion charging system are considerably and non-linearly dependent on initial congestion levels, traffic effects and adaptation costs are surprisingly stable across transport system modifications. The demand for car travel is largely insensitive to supply of public transport and on baseline congestion, and therefore on the total benefit of the charges. For public transport both population size and population density appear to independently influence public transport use. The estimated elasticities being 0,48 and 0,17 respectively. What is not obvious is when supply could improve net welfare. Both an increase in the population and the following crowding can motivate an increase in frequency by the increased net welfare. Large dense cities with more public transport are found to have less car use. The form of the city and its long time use of strategies to facilitate public transport use also decreases the market share of car travel and increases the share of public transport. In large cities density is also found to be correlated with less car and energy use in many cross-sectional studies. The idea that density could induce less car use and CO2-emissions is however challenged by a smaller number of longitudinal studies showing smaller effects from density to car use and CO2-emissions. It has been suggested that some of the effects found in cross sectional studies may not remain in before and after studies. Even though land use policies can be beneficial, their effects are generally less well known than policies addressing transport congestion externalities. As these are better known and likely to be welfare improving the effects of policy instruments associated with congestion pricing, parking pricing, improvements of the supply of public transport are likely to be preferable.