Functional ITS Design Issues

This chapter discusses a number of topics that form the conceptual framework and the building blocks for developing ITS designs as described in the chapters that follow. Topics include: Relationship of ITS design approaches to general transportation planning principles. The impacts of volume, speed, density, capacity issues, recurrent and non-recurrent congestion are introduced and discussed. Insights into the decisions that influence how motorists make diversion choices to alternate routes are presented. The effect of message strength on diversion probability is described. Performance and benefit assessment. Performance measures for evaluation of ITS design alternatives are needed. Marginal analysis and multi-attribute utility analysis are described and illustrated as examples of alternatives to the use of traditional cost benefit analysis. Alternatives for functional analysis. The need for an alternatives analysis is presented along with constraints on the selection of alternatives is described. A matrix identifying the relationship of ITS management concepts to project objectives is presented in order to facilitate consideration of the appropriate ITS treatment to achieve these objectives.