Advanced train control systems enabling single-person crews or driverless trains promise to significantly reduce the fixed costs of operating a train, removing a strong incentive for longer trains. For carload freight traffic, operating a given number of railcars in shorter trains enables railroads to improve service quality and revenue through increased train frequencies or more direct trains bypassing intermediate classification yards. However, operating shorter trains increases the total number of trains on existing rail corridors, exacerbating congestion and decreasing network fluidity. Rail Traffic Controller simulation software is used to quantify the potential mainline delay impacts and relative capacity consumption of shorter trains. Different combinations of train length and train type heterogeneity are tested on representative single-track freight corridors. Results indicate that train control systems with moving blocks can mitigate some of the mainline delay impacts of shorter trains, particularly at a high traffic volume, with a mix of train types and a greater proportion of railcars traveling on short trains. Mid-siding crossovers can further boost the effectiveness of moving blocks in managing complex train conflicts caused by train type heterogeneity. Simulation results are used to perform an example railcar transit time estimation illustrating the trade-off between yard connection time benefits and mainline delay disbenefits, and the thresholds at which different operating strategies produce a net transit time benefit. Understanding the mainline delay impacts of shorter trains can assist railroad practitioners formulating long-term capital investment plans, developing future operating strategies, and improving service quality and market share through a short train philosophy.

支持单人乘员或无人驾驶列车的先进列车控制系统有望显着降低列车运行的固定成本，从而消除了延长列车运行的强烈动机。对于载货运输，在较短的火车上运行给定数量的铁路车厢，铁路可以通过增加火车频率或更多直通火车绕过中级分类场来提高服务质量和收益。但是，运行较短的火车会增加现有铁路走廊上的火车总数，从而加剧交通拥堵并降低网络流动性。铁路交通管制员仿真软件用于量化潜在的干线延误影响和较短列车的相对通行能力消耗。在代表性的单线货运走廊上测试了火车长度和火车类型异质性的不同组合。结果表明，带有移动块的列车控制系统可以减轻较短列车的某些干线延误影响，尤其是在高流量的情况下，混合使用列车类型和在短列车上行驶的较大比例的有轨电车。中间的交叉路口可以进一步提高移动块在管理由列车类型异质性引起的复杂列车冲突中的有效性。仿真结果用于执行示例的铁路运输时间估算，该估算说明了堆场连接时间收益与干线延误收益之间的折衷，以及不同操作策略产生净运输时间收益的阈值。