PRACTICAL LIMITS OF SINGLE-TRACK LIGHT RAIL TRANSIT OPERATION

Increasing urban traffic congestion continues to stimulate interest in exclusive rights-of-way for new transit projects. Today's increased concern with cost-effectiveness, however, has focused attention on light rail transit (LRT) and other transitway technologies that are less capital-intensive than traditional heavy rail rapid transit. For these systems, planners have sometimes turned to single-track operation. Such operations have their limits, however. A planning-level method can identify whether single-tracking is appropriate for a particular application. The spacing and length of passing tracks depends on a number of factors, primarily the scheduled headway and the variability in vehicle travel time. Generalized design conditions, analogous to some levels of service can be considered in terms of maximum running times over single-track sections. For situations in which single-track operation is found to be feasible, the effects of additional practical considerations can be explored. Guidelines can help determine whether these practical considerations are likely to invalidate a solution originally determined to be feasible. Modern LRT and traditional street railways can also be compared in terms of the defined conditions.