The GBP10 billion Channel Tunnel railway between England and France is widely regarded as the most complex land transport system in the world. It features a vast array of sophisticated mechnical and electrical services and safety systems which are more akin to air travel than rail travel but which were essential to satisfy the ever increasing demands of the intergovernmental safety commission. The seven refereed papers in this special issue of ICE Proceedings are written by senior members of the project team. They cover everything from the design and development of the shuttle trains and service tunnel transport system to descriptions of the power supplies, signalling, control and communications systems and tunnel cooling, ventilation, drainage and fire-fighting facilities.