This book concentrates on electric traction, and the stress is on signalling developed for electric rather than steam railways, but there was considerable exchange of practice between the two. The most extensive, modern signalling and communications systems were found on new lines because they were not trammelled by established practice. Modern electric signalling, communications and control were introduced, perfected and integrated into an evolving whole in new electric railways or on steam railways that were electrified.

A.G. Bell, T.A. Edison, G. Stephenson, J. Watt, H.S. Maxim, F.J. Sprague, Z.T. Gramme, W. Siemens, G. Marconi, S. de Ferranti, G.W. Westinghouse and H. Ford are examples of men who gave the world new engineering systems and components. Sprague, more than any other, created the heavy-duty electric railway, as distinguished from the electric street tramway, or the first electrified main lines on steam railways. The considerable achievements of Siemens, Westinghouse, van de Poele, Brush, Daft, Edison, Crompton, Thomson, Hopkinson, Houston and other pioneers are likewise acknowledged. These pioneers turned the electric street railway of 1880 into the electric heavy-duty railway of 1900. The earliest efforts to electrify tramways were done in ignorance of electrical engineering.

The early British electric lines used simple DC system including the City & South London Railway, the Liverpool Overhead Railway, and both the Waterloo & City Railway and the Great Northern & City Railway. Later, these lines were supplied from AC stations when the electric railway network grew sufficiently large to justify large, centralised power houses and when the advantages of AC generation and transmission were recognised. Many electric street tramways continued to be supplied from DC stations until they were replaced by motorbus services, In Britain, the first DC electric lines ran in tunnel under great cities and there was a fear that return currents passing through the ground might damage buried cables and pipes, and an insulated fourth rail was often provided to carry it. It helped to meet the Board of Trade requirements that voltage drop be kept within limits, and was also used to leave the running rails free to carry track circuit currents for working automatic signals. This four-rail system was used on the Mersey Railway and on the London Underground lines, though at first the Central London Railway did not use it. It became standard in London Transport days.

The first electric rapid-transit railways, whether elevated on viaducts over streets as in Chicago or New York, or running in tunnels as in London, faced peculiar problems in the matter of signalling, position monitoring and control. The problems were acute with the tunnel lines, but they could be severe on the twisting elevated lines which curved sharply between the high walls of tenements and warehouses. There was no long-distance sighting ahead of trains, as there was on main lines, and braking distance often exceeded sighting distance. In the early 1890s, the steam-worked rapid-transit railway had reached a practically unsurpassable limit, and electrification was the only means of upgrading performance. This demanded an improved signalling and control system. Manual-mechanical signalling systems were improved and used on electrified rapid-transit railways, but the trend was to integrate signalling, communications and control more closely with the traction system and power supply. Automatic operations were introduced, and the survival of manual working became dependent of electro-mechanical aids and the powered working of distant mechanisms. This was made easier by ready access to electricity supply which was available in the large cities where rapid-transit railways were located.

Heilmann's 'Electric Rocket' established the thermal electric locomotive as a means of electrifying railways without fixed works, and the advantages of using an oil engine to drive the dynamo rather than a steam engine were clear.

The history of signalling, communications and control records many innovations which were tried long before they became common practice. The City & South London Railway (1890) and the Liverpool Overhead Railway (1893) used automatic signalling years before it became usual on general-purpose railways, and the London Post Office Railway demonstrated automatic working of an electric railway some 40 years before urban rapid-transit systems employed it. The Post Office Railway ran driverless trains carrying mailbags over 23 miles of track along a route 6.5 miles long. Passengers were not carried. It was the first automatic electric railway in the world, and was of great engineering significance. There were automatic and semi-automatic mechanical railways through out industry. Typically, wagons were hauled by a chain or cable from a quarry or mine to an unloading staithe or furnace. Many of the operations were controlled by trips or governors, and there was human intervention, as necessary, by an overseer. When labour was cheap, fully automatic operation was not economically justified.

Confronted by the success of General Motors, the steam locomotive builders tried to enter the field themselves. In 1940, with the 'Steamotive' a failure, General Electric and Alco co-operated to produced a 2000 hp AIA AIA diesel locomotive, but the entry of the USA into the World War in December 1941 brought government restrictions on further development. General Motors got all contracts for road (main line) diesels, and General Electric and Alco were limited to producing 1000 hp road-switchers. This restriction greatly hindered the efforts of Baldwin, Lima, and Alco to get into the business of diesel locomotive manufacture. Later, General Electric broke its link with Alco in order to manufacture diesels independently. The American Locomotive Company (Alco) did not have the resources of either General Electric or General Motors to continue diesel development and construction on its own, and it stopped build ing locomotives. It survived as Alco Products, making pressure vessels, pipe work, oil rig equipment and domestic equipment like washing machines. Another big manufacturer of steam locomotives, Baldwin-Lima-Hamilton started making diesels late, lacked a standard design, and suffered from the use of an inferior engine. In volume of diesel sales in the USA, the Baldwin group never held better than third place, after General Motors and Alco-General Electric. It met the same fate as Alco.

Several schemes for railway electrification were proposed between 1920 and 1956 when the modernisation plan for British Railways was published. There were four reports on railway electrification submitted to the government between 1920 and 1951. Each one built on earlier work and each recommended that national railway electrification should use the HVDC system for main line work, and retain the LVDC 'London Standard' system for extensions to existing rapid transit networks.

Large British general manufacturers like English Electric, or General Electric (GB) were well established in the business of electrifying railways and supplying electrical equipment to industry. These manufacturers were well placed to build diesel, gas-turbine and electric locomotives should British Railways need them. These general manufacturers urged the home railways to order diesel and electric locomotives to create a home market within which British industry could develop the skills required for winning foreign orders.

The single-phase 25-kV, 50-Hz railway became a global standard because of rectifier locomotives with DC motors. Without them, HVDC railway would have remained the standard and might have evolved into a 6000-V DC railway as the Russians proposed. The position of the AC system was helped by solid-state power electronics systems, which of course can also improve DC alternatives. Solid state rectifiers and thyristors greatly improved the performance of the rectifier locomotive and dispensed with the troublesome mercury-arc rectifiers.

This chapter discusses the single-phase AC electric mainline railway that linked London Euston to Crewe, Manchester and Liverpool. This first phase of the West Coast Main Line (WCML) electrification marked a culmination and a beginning. It was sometimes described as 'the former steam railway improved by electric traction and the dieselisation of non-electric operations'. Steam traction was surpassed in every way, but the railway's commercial and economic functions dated from the pre-electrification period.