The general aim of the present thesis was to investigate the determinants of car users’ switching to public transport when driving to work. Since the quality of services is particularly low in medium-sized cities, making the car a much more attractive option, the studies focus on car-use in such cities.

Four studies were conducted. In the first (Paper I), an Internet survey addressing what people using their cars to commute to work in a medium-size city believe would make them reduce their car-use as well as what improvements to public transport services they believe would make them use those services was conducted. The results showed that, the further to work and/or bus stops - the more the participants desired increased frequencies and shorter travel times, but less often lower fares.

In the second study (Paper II), using a web-based experimental simulation, participants were given the task of planning their travel to and from work, including the performing of additional activities in accordance with predetermined agendas. The main results of this were that shorter travel times and good access to bus stops led to greater bus use while constraints imposed by a busy daily agenda led to greater car-use, in particular if car costs were low.

In the third study (Paper III) a scale for measuring satisfaction with travel was developed. A new measure of travel-related subjective well-being (SWB), a 9-item self-report Satisfaction with Travel Scale (STS), was developed. The results showed that STS is reliable and differentiates between changes in travel conditions.

In the fourth study (Paper IV) which attributes other than time and cost contribute to the preference of car over bus in the choice of travel mode was investigated. Using STS, developed in Paper III the effect of different travel modes on satisfaction with travel was studied.

The conclusions of this thesis are that a public transport system must appear attractive, not only to its present users, but also to prospective users who currently use their cars. To appear attractive, it must not be too expensive and must have timetables and routes that allow users to travel in an efficient manner. One measure that can be used to force commuters out of their cars is higher car-use costs; however, car-use costs may need to be substantially higher than the cost of using public transport in order to be effective. As the present research has indicated, the perceived difficulty of using public transport is also an important factor. Raising car-use costs will thus be insufficient unless changes are made to public transport services. A factor complicating this is activity patterns, which are often complex. As has been indicated in the present research, the more complex the activity pattern - the more the car is used as a means of transport.