Service optimization for bus corridors with short-turn strategies and variable vehicle size

An optimization framework for intermediate-level planning of bus operations on a given corridor is presented. Service patterns over different operation periods, which include short-turn strategies (full-length and short-turn line) and variable vehicle size, are considered. Variables optimized are: positions where turnbacks are operated, vehicle size, frequencies (by operation period) and, where bus arrivals are regular, relative offset (by operation period) of full-length and short-turn line, and fare. The objective function is the net benefit represented by benefits that accrue to the users for lower average waiting times minus operator's costs not covered by fares. A numerical procedure to solve the problem is provided. An application of it to a case representative of radial corridor conditions shows the effects on service patterns and the trade-offs over operation periods between users' and operator's costs, stemming from different design criteria according to the weights attached to the two players.