This analysis presents a methodology for measuring the efficiency of train dispatching as a product of three variables: (a) the type of train control system (measured by latency, defined here as the interval between occurrence of a schedule deviation and initiation of corrective action); (b) the physical capacity of the route (track kilometres per route kilometres); and (c) train minutes per route kilometre (a measure of both capacity and dispatcher competence). A mathematical relationship among these three variables is postulated, and a log-log regression analysis is used to develop coefficients that relate each of the three independent variables to dispatching efficiency. Dispatching effectiveness, calculated by placing track kilometres per route kilometre, train minutes per route kilometre, and latency at their mean values, was 71.3 percent (the mean latency was about 17 min). At a latency of 3.5 min, average effectiveness is 81.3 percent. Examples of the trade-off between latency and effectiveness and between track capacity and effectiveness also can be calculated. To quantify the dollar benefits of such an increase in dispatching effectiveness for US railroads, further analyses were carried out. Based on a previous study of Burlington Northern operations, train delay costs ranged from $163/hr to $266/hr. To simplify calculations, a value of $200/hr is used. According to US railroad statistics, there are about 21 million train hours of traffic each year. Benefits available from installing communications-based train control are calculated in terms of additional train minutes per route kilometre available with an increase in dispatching effectiveness based on this analysis. (A)
Samenvatting