The British Railways project is complicated by two factors which are absent from most constructional undertakings. First, a railway system is not a series of separable parts; it is an organic whole. One cannot isolate a branch of activity, overhaul it, and then move on to the next. Too many elements are interlinked and have to be considered together. For instance, it is no use having new diesel trains unless you have trained crews, specialised maintenance staff, fully equipped maintenance depots, refuelling points, and so on. All these matters must proceed in step."

• Track;
• Signalling;
• Motive power - diesel traction;
• Motive power - electric traction;
• Passenger train services;
• Passenger stations;
• Shipping services;
• Catering;
• Freight depots and marshalling yards;
• Freight train services;
• Maintenance depots.