Just 38 years after the birth of the modern railway in 1825, the first underground railway was opened in London. In case anyone is unaware, the Underground is usually known as The Tube, strictly a term for the small gauge deep lines. Here, we will canter through 162 years of its development and innovation that has helped shape London as a world class city, with occasional references to political events for context, but this is just an outline.
The first 100 years (approximately)
The Metropolitan Railway from Paddington to Farringdon opened in 1863 with the aim of reducing on-street congestion. Originally, it was a partnership between the Metropolitan Railway and the Great Western Railway, the latter keen to extend its broad gauge (seven-foot) lines into the city of London.
The parties fell out and no broad gauge ever ran to Farringdon. It was built using the cut and cover technique – digging a huge trench in the road, building reinforced sides, and then reinstating the road surface as the tunnel roof.
It was operated by steam trains and contemporary reports suggest that conditions underground, even with steam trains, were not as unpleasant as in the street at that time. Incredibly, steam haulage on the Metropolitan line survived until 1961 (Rickmansworth to Amersham).
Since then, the London Underground has grown into a vast system and has witnessed, and often led, many technical innovations. Electrical and telecommunications systems have developed hand-in-hand with metros and, even in 1863, the electric telegraph was a feature.
The Metropolitan Railway was a great success and was extended both east and west. A different company, the Metropolitan District Railway, built a line from Gloucester Road to Tower Hill allowing the Circle line, a joint operation with the Metropolitan Railway to start running in 1870, still steam hauled. As an aside, the original builders of these cut and cover steam lines incorporated many ventilation outlets which proved to be very beneficial more than 130 years later when air-conditioned trains were introduced.
Disruption
It became clear that the scale of disruption caused by cut and cover construction could not be tolerated if the underground was to be expanded. It helped that London is built largely on clay, and engineer James Henry Greathead invented a tunnelling technique which used a circular shield to protect miners when digging into the clay prior to erecting cast iron linings.
Cost of tunnelling has always been an issue. The City and South London Railway (C&SLR) was the first line dug with the Greathead shield. The tunnel was only 3.2 metres in diameter but this was tolerable as the Victorians were quite short. The C&SLR initially ran from King William Street in the City to Stockwell and opened in 1891. It was electrically powered using locomotives hauling cars known as padded cells due to their tiny windows. Passengers accessed the cars via lattice gates at each end of each car, controlled by a staff member.
In 1900, the second tube line opened. The Central London Railway (CLR), running between White City and Bank, was originally known as the ‘Twopenny Tube’ because of its flat fare of two pence (less than one pence in 2024 currency). Its tunnels were slightly larger than the C&SLR’s at 3.32 metres diameter. Along with extensions, the original tunnels were enlarged during the 1930s to approximately the standard diameter of 3.56 metres. Again, locomotive-hauled trains were used, although trains were longer and its locomotives were more powerful and heavier, the latter factor leading to complaints about vibrations in buildings above the line.
The CLR pioneered so-called hump stations where the lines had down gradients exiting from stations aiding acceleration, and up gradients approaching stations reducing brake wear.
Electrification
In the meantime, there was pressure to end steam haulage underground. There was debate between the Metropolitan District and the Metropolitan Railways about the type of electrification to use. The Metropolitan Railway proposed AC power whereas the Metropolitan District Railway proposed a nominal 600 VDC insulated return system using two conductor rails. After arbitration by the Board of Trade, the latter system was chosen. Power stations were built, respectively at Lots Road, Chelsea adjacent to the Thames and at Neasden.
Electrification was implemented in 1905, along with the adoption of multiple unit control and the adoption of powered signalling and tripcock/trainstop protection to stop a train if it passed a signal at danger (SPAD). Many of these innovations were imported from the USA following the influence and ownership of the American, Charles Tyson Yerkes.
Yerkes was a key figure in the history of London’s Tube described by the London Transport Museum (LTM) thus: “Yerkes used shrewd and sometimes shady tactics that proved necessary to realise a modern Tube network for the twentieth century. He founded the Underground Electric Railways Company of London (UERL) in 1902, which brought together several modes of transport under one umbrella, ultimately moving towards a unified and cooperative transport system.”
When originally built, cut and cover station platforms were accessed by stairs, and deep tube platforms by lifts which were sometimes hydraulically operated. In 1911, the first escalators were introduced to serve the Piccadilly line at Earls Court.
While there was some initial reluctance, the public soon took to them and the escalators’ ability to move large numbers of people meant that many central London stations were reconstructed over the following decades to replace lifts by escalators. This has left stations with many abandoned shafts and passageways which have often been adopted by engineers for ventilation or other purposes. The LTM runs a popular programme of tours to many of these sites branded Hidden London.
Sliding doors
By 1919, the central parts of what became the Piccadilly and Bakerloo lines had been built and the period following the end of the First World War saw the introduction of the first trains with compressed air powered sliding doors. It would take until the early 1950s until the last train with hand worked doors was withdrawn.
After various consolidations and company amalgamations, by 1920 the UERL controlled all lines apart from the Metropolitan Railway. The C&SLR had been extended south to Tooting and northwards to Euston. In the 1920s it was decided to amalgamate the Charing Cross, Euston, and Hampstead line with the C&SLR to become the Northern line we recognise today. A new depot in the ‘village’ of Golders Green was opened to receive the first of what became a large fleet of so-called standard stock built with various designations from 1923 and 1934.
Interestingly some of those vehicles were delivered to the depot using steam traction engines. Although, in practice, the trains were far from standard, they could couple to each other. The post-1930 standard stock incorporated innovations such as electro-pneumatic brakes (also retrofitted to earlier trains).
1933 saw the formation of the London Passenger Transport Board, an arm’s length public company that took over the Underground Group, the Metropolitan Railway, all bus, trolleybus and tram operation in Greater London. Its chairman and managing director were Lord Ashfield and Frank Pick (pictured below), respectively. The two leaders created an integrated organisation, developing and/or influencing standards many of which are still relevant today.
Suburban development
The 1930s brought many extensions to serve and/or promote London suburban development, although some of the extensions were not completed before the Second World War and some were abandoned following the creation of the green belt after the war. An important development of the small gauge tube trains was moving all the electrical equipment from a large compartment behind the driver’s cab onto the underframe. This allowed almost one extra car length of passenger accommodation on a seven or eight car train. Prototype trains, including an unsuccessful attempt at streamlining, were built in 1935, leading to a large order for the 1938 tube stock (with further cars built in 1949).
These operated on the Northern, Bakerloo, and Piccadilly lines, and even on the surface gauge East London line for a while. The last two trains were withdrawn in 1988 after 50 years’ service, although one lovingly restored four-car set remains in active service with the LTM. This type of tube train configuration was to last for over 90 years and was pioneered by engineer William Sebastian Graff-Baker.
The District, Circle, and Hammersmith and City lines also received new trains in the 1930s. These large profile trains, O and P stock, featured distinctive flared sides in keeping with the style consciousness of that decade.
However, the biggest innovation was the Underground’s first use of regenerative braking, long before power electronics made this feature routine. This was provided by Metadyne machines, a type of DC rotary transformer. Each one weighed four tons and cannot have been all that reliable as, in the 1950s, conventional resistance controllers almost identical to those on the 1938 tube stock were fitted instead.
Further innovation
In the 1950s, even though finances were tight, innovations continued. For the District line, the R stock was developed which looked almost the same as the previous O and P stock, and the first batch was of steel construction. The second batch, known as R49, used aluminium construction for the first time and every car was motored.
In contrast, the 1950s tube stocks retained steel underframes although unpainted aluminium body panels were employed and – innovative for its time – rubber suspension was used on the bogies, a feature that has persisted ever since.
This decade was also a time of innovation in signalling and control aimed at more efficient operation. The department was led by Chief Signal Engineer Robert Dell. In 1957, the first programme machine was introduced. This was a device where the timetable was encoded on a punched roll of material which moved across contacts to control points and signals somewhat like a punched roll in a player-piano.
They were a key element in the development of operational centres controlling each line rather than individual signal boxes, but have now all been replaced by computers.
Victoria line
In the 1960s, after nearly 20 years of planning, funding was found to build the Victoria line. With the benefit of hindsight, it was wrong to build it to tube gauge as by today’s standard the trains and stations are too small. But, at the time, funding was tight and the cost of building bigger tunnels was deemed to be too high. There was a lot of innovation in civil engineering. Test tunnels were built in 1960 using an experimental, hydraulically powered, rotary shield ‘drum digger’ which was a forerunner of today’s tunnel boring machines.
Concrete tunnel lining segments were used for the first time too, and there were other innovations. The new ticket hall at Oxford Circus station was to be located under the busy road junction and the Underground’s engineers developed a so-called Umbrella Bridge to allow construction to take place without interrupting traffic.
The line was laid out largely ignoring streets, unlike most previous lines, allowing shallower curves and the two final termini (Walthamstow Central and Brixton) included overrun tunnels and shallow angle crossovers on the station approaches allowing trains to run into these stations on the normal braking profile. These features enabled efficient operation of the world’s first automatically controlled passenger railway. The technology for this was largely developed by the Underground’s engineers and was manufactured by the Westinghouse Brake and Signal Company (WB&SC, now Siemens Mobility). This system was electronic, but in the days before integrated circuits let alone microprocessors!
The automatic 1967 tube stock trains (the first tube trains with rheostatic brakes) were to be operated by one person and there was a requirement for continuous communications between the control centre and drivers. Whether because of unavailability of frequencies or concerns about propagation of radio signals through tube tunnels, it was decided to use a system where the audio signal was sent to/from the train via a frequency modulated ‘carrier wave’ system superimposed on the conductor rails/collector shoes (think Powerline plugs for distributing home networks over the mains cables).
Other innovations included CCTV to help the driver check that the rear of the train was clear before closing the doors; trainborne public address; and a train-to-train radio system to allow the driver of a failed train to speak directly to the driver of an assisting train.
The first century of Underground innovation in London was marked by significant advancements and milestones. From the pioneering days of the Metropolitan Railway to the later efficient, and expansive network, the London Underground has continually evolved to meet the needs of its passengers. Innovations in tunneling, electrification, and train design have all contributed to making the Tube a world-class transportation system.
As we look to the 1970s onwards, electronics, computers and systems integration will become significant features, demonstrating that the London Underground remains a vital part of the city’s infrastructure.
To be continued…
All historic images: London Transport Museum Collection