Rapid Transit Interstation Spacings for Minimum Travel Time

Abstract

Several factors influencing the optimal interstation spacings for line-haul passenger transportation, for example, rapid transit or commuter railroads, are analyzed with respect to the objective of minimum total passenger travel time. The study concentrates on a case in which the population of an area commutes to one central point. The number and locations of stations at which the commuters board the trains for their travel to the central terminus are to be determined so that the total time of all passengers—from their origins to the destination—is minimal. The model incorporates as parameters: passenger (“population”) distribution along the line, access speed, dynamic characteristics of the train, standing time of the train in stations, and intermodal transfer time at stations. In general, the spacings are functions of the ratio between the number of passengers traveling on the train and those wanting to board or alight. The optimal station locations satisfy a set of simultaneous difference equations. Algorithms for numerical and graphical solutions for several different sets of parameters are presented and demonstrated by examples. For uniform population along the line, spacings increase in an arithmetic progression in the direction of passenger cumulation. In all cases density and distribution of stations have high sensitivity to the access-to-station speed.

Assessment of an Optimal Bus Stop Spacing Model Using High Resolution Archived Stop-Level Data

“…Large bus stop spacing minimizes passenger in-vehicle time but reduces the accessibility of the system. Stop spacing has been studied in terms of minimizing transit user's time, and evaluating trade-offs between access and in-vehicle time (5,8,11,(14)(15)(16)(17). In particular, based on Newell's concept (10), an aggregate total cost function was developed including:…”

“…Based on this basic model conceptualized by Newell (10,14), the spacing of a TriMet bus route is examined using archived Bus Dispatch System (BDS). An optimal spacing is computed for the route as a basis for transit service improvement and a sensitivity analysis is performed aimed at assessing the costs and benefits of changing the stop spacing.…”

Approximate procedures for planning public transit systems: A review and some examples

“…Holroyd (1967) formulated a general model for a bus system operating on a rectangular roadway network. Vuchic and Newell (1968) provided a clear description of the modelling procedure in their analysis of transit station spacing along a fixed route. They presented both numerical and graphic solutions to two problems: the minimization of total travel time and the maximization of system ridership.…”

“…The common roadway pattern outlined in Figure 3 limits the obvious bus stop locations to intersections at 500 foot intervals. Application of a typical model (Vuchic and Newell, 1968) determines the optimal spacing in this environment at about 200 feet. The passenger demand will likely be greatest at the important intersections and would be less likely to be high at the intermediate locat ions.…”

“…In the Portland case the block sizes are so small that the train length is limited to two 76 passenger cars. Vuchic and Newell ( 1968) acknowledged this problem and provide an alternative to the iterative process listed above. The author's experience is that the critical distance for light rail cars is approximately 650 feet.…”