"Before and After" Studies in a Turbulent Environment - a Dynamic Approach
K N Kjoerstad and B Norheim, Institute of Transport Economics, NO
In 1996, the Norwegian Ministry of Transport and Communications initiated a funding scheme for public transport experiments. In total 14 experiments in different cities in Norway are included in this funding scheme for the period of 1996-2000. The Institute of Transport Economic (TOI) has developed a basic evaluation for these experiments. The basic evaluation consists of a passenger surveyand a travel survey with panel data. Both surveys are conducted before and after the implementation ofthe measures and we have also investigated the changes in the attitudes towards and knowledge about the public transport system in the area, and the interaction between usage, knowledge and attitudes.
The main challenge for this evaluation scheme is to find the isolated effect of the measures, corrected forthe effect in a turbulent environment. This applies both to changes for the individual, such as family situations, employment and financial situations and external effects such as fuel prices, parking conditions etc. The latter are by no means insignificant for the conclusions we have drawn from this initiative.
The analyses show that the "external" conditions, i.e. factors which are not connected with the concrete measures, have affected the use of public transport in a negative direction in all areas, but the packages of measures have dampened this development, and for Stavanger/Hundvaag, a strong decrease has turned to growth. The evaluations have also revealed a reduction in the car use. This effect has primarilybeen noticed in Stavanger/Hundvaag, and has been more marginal in the other areas.
There is a strong connection between passengers? satisfaction with the measures and changed travel activity. Increased bus use can be traced directly back to the improvements which have been carried out, and in the first instance to increased frequency which alone explains over half of the passenger growth.
However, it is easier to "lose" passengers by making public transport worse than it is to gain new passengers by improving public transport. This asymmetry will be investigated in more depth when more experiments are included in the database. The analyses also revealed the interaction between knowledge, attitudes and mode choice, and it was in fact a reduction in negative attitudes and not more positive attitudes, which made the greatest effect on changing travel modes.
This paper will discuss the problems and challenges of "Before and After"-studies in a turbulent environment and the benefit of using a three steps estimation procedure and overlapping surveys for the evaluation of these experiments. The paper is based on the first two years of evaluation including four cities/packages of measures, and will also present the differences between the gross and net effect on the mode choice, depending of the evaluation methods used.
Association for European Transport