摘要
全世界铁路运输流量密度一直在增长，特别是货运和高速铁路。传统的信号系统难以应对这种复杂状况，而造成了列车的延误和车次的取消，有时还会带来危险的列车超速。最严重时还出现了故障的信号系统造成列车脱轨或碰撞。美国和欧洲的专家正在从计算机化的通信系统中寻求解决方案。
Traffic densities are building up all the time on the world＇s railways, particularly on freight and high speed lines. Traditional signalling systems are finding it hard to cope,leading to delays and cancellations, and sometimes dangerous overspeeding. In the worst cases, defective signalling can cause derailments and collisions. In the US and in Europe, solutions are now being found in computerised communications systems.
