Chapter 39: Optimization of Transport Strategies^a

Optimization implies identifying the best strategy to meet a given policy objective. As noted in Chapter 14 on integrated transport strategies, any strategy is likely to involve a set of policy instruments, and to draw on the interaction between those instruments. The process therefore involves specifying one or more objectives, combining them into an objective function, selecting a wide range of possible policy instruments, and varying their levels, in combination, until the maximum value of the objective function is found. This set of levels of policy instruments will represent the theoretical best strategy. In practice, decision-makers will usually not be able to implement such a strategy, either because elements of it are unacceptable or because of constraints such as availability of finance. Practical optimization therefore typically involves identifying the combination of policy instruments and levels that best meets a given set of policy objectives, subject to satisfying a set of policy constraints.