MODAL DIVERSION. IN: HANDBOOK OF TRANSPORT SYSTEMS AND TRAFFIC CONTROL

The reasons that passengers and freight operators choose one form of transport over another can be broadly classified into influences that are related to time, cost and service quality. The challenge for any investigation of influences on modal choice is to identify the attributes that describe each class of influence and to place weights on each attribute to establish its relative influence. This paper reviews the most popular methods available to evaluate modal attributes and market segment in the explanation of modal split and modal diversion. The discrete-choice modeling approach is used to study influences on modal diversion. Behavior responsiveness of individuals and firms to changes in the levels of all influences on modal choice can be calculated with the use of an elasticity calculation (typically obtained from a modal choice model or a before-and-after monitoring study of the impact of a policy change) or by calculating changes in choice probabilities and shares using a modal choice model. The methods used to establish the weights for each attribute and the types of policy outputs that analysts typically seek from such models (such as values of travel time savings, share elasticities and market shares) are presented.