| The time-area concept captures in a single unit the quantity of ground area consumed for movement or storage of vehicles, as well as the amount of time for which the area is consumed. Previously this concept was developed and used only for special cases, pedestrian facility analysis having received the most attention. Therefore, general equations applicable for almost any surface transportation mode were needed. Separate formulae are developed for vehicles which can be modelled as discrete objects moving without significant mutual interactions, and for vehicles which must be modelled as a continuous flow. Example adaptations of these formulae to specific modes are presented. Methods for identifying the transition between discrete and continuous flows and analyzing combined flows are also included. Other practical methodologies for the use of the formulae, such as treatment of initial and final conditions, computational algorithms, and simulations, are discussed. The time-area requirements of urban modes are compared. Normalization formulae for time-area consumption to a common basis, such as per passenger or per unit of transportation work, are also developed, including the impact from freight vehicle flows on passenger vehicle flows. Time-area consumption for several urban transportation modes under selected conditions are presented in graphical form. Several applications are outlined, including urban planning and traffic engineering. Operational analysis over multiple intersections is presented in contrast to traditional methods of analyzing each intersection separately; the capacity consumption by both moving and stationary vehicles is unified through the time-area measure. Applications to road use pricing are discussed at length; a comparison with marginal cost based pricing is made using both a net-benefit and qualitative approach to show that pricing based on time-area consumption offers such advantages as pricing proportional to resource used, a price increase disproportionate with distance to discourage urban sprawl, and relative ease of public understanding. |
