The thesis aims at developing new, alternative approaches and methods based on suggestions and ideas originating from moral philosophy and philosophical decision theory. More precisely, the thesis aims at investigating the rationality of transport policy decisions, including goal-setting and performance evaluation. Paper I discusses rationality in road safety policy. Problematic features are identified and discussed. The paper argues that the Swedish road safety goal is rational, since it is action-guiding and achievement-inducing. This follows by observing that the goal satisfies the (...) criteria of precision, evaluability, approachability, and motivity. The paper states that previous accusations of irrationality have been unnecessarily imprecise, since no reference is made to independently developed criteria of rational goal-setting. Paper II discusses the Swedish transport policy goals, and the role of social welfare in rational policy decisions. Goals often come into conflict and trade-offs must be rationally and consistently managed. Policy decisions are outcomes of political processes. In the case of policy goals and decisions, the agent is society. This introduces the problematic concept of social welfare, which itself is an ambiguous goal with many meanings. Whether a decision is rational or not depends on whose perspective one takes on – that of society as a whole or that of the actual decision makers. Paper III aims at investigating six different procedures for resolving goal conflicts: weighted average, lexicographic preference, conditional lexicographic preference, absolute restriction, generalised prioritarianism, and partial comparability. Criteria for selection, according to the respective procedures, are formulated and summarised in a table. The six procedures are contrasted with respect to their tendency to rule out possible sets of alternatives as being not choiceworthy. (shrink)