Choice sets of individual travellers play a paramount role in analyzing travel choice behaviour. Choice sets are defined as the collection of travel options perceived available by individual travellers in satisfying theirtravel demand. From a variety of studies it is well known that the size and composition of choice sets do matter in cases of choice model estimation and demand prediction. Incorrect choice sets (e.g. because of captivity)can lead to misspecification of choice models and to biases in predicted demand levels. While this has been demonstrated for relatively simple choice types such as mode choice, it may be assumed that it holds as well for the more complex case of route choice. The critical role of choice sets inchoice modelling has given rise to profound research into choice set modelling in the transportation field, although largely confined to mode choice. These insights gained on choice set modelling and choice set generationcannot simply be transferred to the route choice realm. For a variety of reasons the specification of route sets for route choice modelling is different and more complex, reason why this topic deserves special attention from researchers and practitioners. A number of topics related to the modelling and generation of route choice sets are considered, specifically for application in large networks including multi-modal networks. An attempt is made to synthesize existing knowledge on this topic based on a thorough literature review into a single conceptual framework giving ample attention to a theoretical underpinning. Recent new approaches to choice set generation for large networks are investigated. The one group of promising approaches is the constrained enumeration procedures. Another promising line of research is combined stochastic (which may include several elements) anddeterministic path search. In what respect route choice sets differ from other travel choices is summarised, with the implication that some proposed choice set modelling approaches cannot be adopted for routes. Then it isargued that it is necessary and advantageous to distinguish the processesof choice set formation and choice on the part of the traveller. Before going into more detail of choice set modelling, the various notions of choice sets and the various purposes for which choice sets may be used are outlined. Two approaches will be described in somewhat more detail, namely a deterministic constrained enumeration approach and a doubly stochastic path generation approach. For both of these approaches some indicators for their empirical validity will be presented derived from applications to various uni-modal and multi-modal networks. Two road network cases covering the region around den Haag in Holland and the Copenhagen region in Denmark, and two similar multi-modal public transport cases in the same areas are used as examples. It is shown, that the new generation of choice set generation models indeed improve the generation of routes compared to prior methods. For the covering abstract see ITRD E137145.
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