Supporting Decision Processes Related to Transport: from CBA (cost Benefit Analysis) to MCDA (multi-criteria Decision Analysis)
M L Galves, University of Campinas, BR
This paper aims at emphasizing the importance of structuring in the context of multiple criteria decision analysis and showing that it can provide a comprehensive and rich support to decision processes related to transport projects.
Transport is a major component of economic activity, both in itself and as an input factor to most other economic activities. It further plays an important role in the daily life of citizens. However transport systems have many effects on the environment and on human health such as air pollution, noise, accidents and fragmentation of natural habitats. They also contribute to local and global pollution problems. Hence the integration of environmental concerns into transport decisions is a key to improving environmental performance and moving towards sustainable development.
Decision processes related to transport projects involve considerations on technical, social, environmental, economic and political issues. They are characterized by many actors and multiple objectives which are often conflicting.
Cost-benefit analysis (CBA) has been traditionally applied to the evaluation of transport projects, such as new roads and high-speed rail links. CBA is considered a sound evaluation method but it has important limitations. The emphasis on monetary assessment tends to reduce the range of effects to be taken into account in the analysis. Effects may be ignored not because they lack importance but because they cannot be valued in monetary terms.
Due to the complexity of the situations associated with transport, multiple criteria decision analysis (MCDA) has been increasingly used for supporting the decision-making process.
MCDA can be divided into three main phases: structuring the decision situation, evaluation of alternatives and recommendation for the most suitable alternative (or alternatives). Although they are interacting phases, structuring precedes and prepares the evaluation and recommendation phases. It is that part of the decision-making process in which an analyst or facilitator helps an individual or group think about and understand a situation which requires a decision.
Practitioners and academics point out that greater attention needs to be paid to structuring in MCDA, recognizing that if structuring is improved the quality of the decision outcome will be better.
This paper aims at emphasizing the importance of structuring and showing that it can provide a comprehensive and rich support to decision processes related to transport projects. Overall characteristics of the CBA are initially presented. Then some theoretical aspects related to structuring are analysed and the activities involved in such a process are described.
Structuring is also illustrated by an example on the high-capacity rail system planned for the city of Curitiba, Brazil. After a short description of the project, the effects taken into account in CBA are presented and analysed. Some possible structuring elements of this decision situation are proposed and compared with the effects computed in CBA. The purpose is to show how the various effects of the project (e.g. technical, economic and environmental ones) can be explicitly considered and integrated by means of a multi-criteria decision aiding approach.
Association for European Transport