Approaches to dynamic transport planning

Dynamic transport planning refers to the analysis of the problem of choice of implementation date of the construction or improvement of transport facilities. This analysis may also include consideration of stage construction or progressive improvements in quality and/or capacity over time, beginning from some relatively low standard. A transport facility is defined as a vehicle (e.g., automobile, airplane) or a supporting facility (e.g., highway, port). There appears at present to be a serious lack of any truly comprehensive evaluation of the essentials of the problem of choice of implementation date. It is the intent of the ensuing presentation to help to rectify that situation by introducing new concepts which structure the timing problem. The concepts are based on a suggested classification of future traffic and definitions of independent and indivisible facilities. In addition, volume of traffic and benefits of a transport facility are recognized to be dependent on calendar time and the facility's age. Presently, no uniform theoretical framework exists for establishing the optimal time for constructing new facilities or improving existing ones. A framework based on the aforementioned concepts is introduced. It distinguishes between the phasing of projects through time in the absence of budget constraints and this phasing in the presence of such restrictions. The specific procedures suggested in this paper for the analysis of the problem of choice of implementation date apply to any individual transport facility and tend to unify the concepts involved in dynamic transport planning. The article concludes with a survey of current approaches to dynamic transport planning and discusses these in the light of the above framework.