British electric multiple units

An electric multiple unit is an electric train that does not have a separate locomotive and are typically passenger trains with accommodation in every vehicle and a driving position at each end. The term can also be used to describe a train such as the Advanced Passenger Train that was a permanent formation with a non-driving power car. two thirds of the rail passenger cars used in Britain is part of an electric multiple unit.

Electric railways began in Britain in 1883 and the first electric multiple unit ran on the Liverpool Overhead Railway in 1893. In the early 20th century systems were developed where all the motors on a train could be controlled by a low voltage signal from any cab. Due to problems using steam locomotives underground, the underground railways in London and Liverpool were early adopters of 600V DC electric traction and by 1907 underground railways in London and some provincial cities were running electric trains. A 6.7 kV 25 Hz overhead system was also used from 1908. After the railway companies were grouped in 1923, the Southern Railway greatly expanded the 3rd rail DC electricification, replacing some early AC electrification. Overhead lines at 1500 V DC were planned and installed just before and after the second world war. The early multiple unit cars, similar to contemporaneous railway carriages, were constructed of wood with hinged doors and accommodation could be provided in saloons or compartments. As time went on more steel became to be used in carriage construction.

After the second world war the railways were nationalised and the 25 kV 50 Hz overhead system became to be installed, eventually replacing the earlier 1500 V DC systems. South of London, the Southern Railway 3rd rail electrification system continued to expand.

Early electric railways
The Volks Electric Railway, the first electric passenger railway in Britain, opened in 1883 as a short 2 ft gauge electric railway running for 1/4 mi in Brighton. At first electrical power at 160 V DC was supplied to a small car using the two running rails, but it wasn't long before a third live rail was added, a sliding shoe making contact to the top.

The City and South London Railway, a 3.2 mi long deep-level tube railway, opened in 1890 with carriages hauled by electric locomotives powered from a third rail beneath the train energised at 500 V DC. In 1893 the Liverpool Overhead Railway opened with two lightweight passenger cars coupled together; on each car one bogie was powered with a single 60 hp motor that was powered from a third rail between the tracks at 500 V DC. Any number could be coupled together and all the motors controlled by the driver at the front. In 1898 the deep-level Waterloo and City Railway also opened with electric multiple units, a central third rail providing DC traction current at 500 V to 530 V. The traction current for the two motor cars could be controlled from either driving cab, but the Board of Trade became concerned about the fire risk presented by the eleven power cables carried on the roof of the train and bared further installation of similar systems in deep-level tubes. Therefore, when in 1900 the Central London Railway opened its deep-level tube railway, electric locomotives hauled carriages.

In 1900 the Metropolitan Railway and the District Railway ran an experimental multiple unit in passenger service for six months. A four rail system was used, two rails outside the running rails providing the traction current at 500–550 V DC Only the traction motors in the leading motor car were used, the trailing motor free-wheeled. In 1901 a Metropolitan and District joint electrification committee recommended a three-phase AC system with overhead wires. Initially this was accepted by both parties, however the District needed to raise finance and found an investor in 1901, the American Charles Yerkes. Yerkes soon had control of the District Railway and his experiences in the United States led him to favour DC with a track level conductor rail pickup similar to that in use on the City & South London Railway and Central London Railway. After arbitration by the Board of Trade the DC system was taken up.

Low voltage multiple control
In 1897 Frank J. Sprague demonstrated a system where a low voltage control signal from any driving position controlled all the motors on a train that had been developed for the South Side Elevated Railroad in Chicago. This electro-magnetic system was developed in Britain by British Thomson-Houston (BTH) and first used in Europe in 1902 on the Central London Railway when they changed over to multiple unit operation to solve a design problem with their locomotives. Westinghouse Electrical developed an electro-pneumatic multiple unit system that used a lower control current and when in 1903 the District Railway opened its line from Acton Town to South Harrow with experimental multiple units these used control systems from BTH and Westinghouse. After these trials the District Railway selected BTH equipment for its B Stock.

The underground Mersey Railway started an electric service on 3 May 1903, electrified by British Westinghouse Electric with electrical equipment shipped from the US. A four rail DC system was installed, with a positive outer rail and a negative return rail between the running rails.

In London the Great Northern & City Railway was a 3+1/2 mi underground line from Moorgate to Finsbury Park. Electric multiple units with BTH electrical equipment were used from the opening on 14 February 1904; these picked up traction current from conductor rails both sides of the running rails. The.

When the Lancashire and Yorkshire Railway (L&YR) was considering electrification of the suburban Liverpool railway, concerns were being expressed, especially in the railway press, that engineering developments in Britain were being overtaken by electrification projects in America and Switzerland. The Preston based Dick, Kerr & Co. was made responsible for the traction systems and the L&YR built the rolling stock. A 625 V DC four rail system was adopted, the live rail positioned outside the running rails with a return rail, cross-bonded to the running rails, between the tracks. The two driving motor cars each powered by four 150 hp (110 kW) motors directly controlled from a driving cab at either end of the train. Electric services started on the line between Liverpool Exchange and Southport on 22 March 1904.

The North Eastern Railway (NER) began using its electric multiple units between New Bridge Street and Benton and 29 March 1904 and from 25 July 1904 over a circular route between Newcastle Central and Tynemouth, electrified with a third rail at 600 V DC. The multiple units, fitted with BTH electrical equipment, were built at the NER Carriage Works at York with clerestory roofs.

The Metropolitan Railway began its electric services from Uxbridge to Baker Street in 1905 with Metropolitan Railway electric multiple units using Westinghouse electric equipment; these ran off-peak as 3-car units with a motor car and a driving trailer. Twenty trains with BTH equipment were ordered for the Hammersmith & City line, jointly operated with the Great Western Railway and Met. From June 1905 to the end of 1905 electric multiple units replaced steam on all District Railway services. In 1906-07 three deep-level tube railways opened in London: the Charing Cross, Euston and Hampstead Railway, Great Northern, Piccadilly and Brompton Railway and Baker Street and Waterloo Railway. All subsidiary companies of the Underground Electric Railways Company of London the trains were built by different manufacturers to a similar design. Accommodation in open saloons was accessed by end platforms protected by lattice gates and power was collected from a 550-600 V DC four rail system and controlled with BTH equipment.

Early overhead AC electrification
In 1908 the Midland Railway introduced its electric units that used an overhead line energised at 6.7 kV 25 Hz AC. From 1909 the London, Brighton and South Coast Railway (LB&SCR) also used an overhead line energised at 6.7 kV 25 Hz. The first section to be electrified was the South London Line connecting London Bridge with Victoria via Denmark Hill, which was opened on 1 December 1909. The new service was marketed as 'The Elevated Electric' and was an immediate success. By 1921 most of the inner London suburban lines were electrified and lines to Coulsdon and Sutton opened on 1 April 1925.

For the LB&SCR services three types of stock were built. The initial South London (SL) stock was introduced as 3-car trains, but after 1910 the first class trailers were removed and these subsequently ran in 2, 4 or 6 car formations. In 1910 the CP stock was built for the Crystal Palace route; these normally ran as 3-car units. The later five car CW stock had motors fitted in driving motor luggage vans, passenger accommodation being provided in trailer cars.

From 1913 to 1916, the L&YR operated an experimental electric service in the Manchester area on the line between Bury and Holcombe Brook. The equipment was provided by Dick, Kerr & Co., who was developing its products for overseas sales. The system used was 3.5 kV DC overhead and two two-car units were built. After these trials, the L&YR electrified the Manchester to Bury line using 1200 V DC with four rails. This opened in 1916 and in 1918 the branch to Holcombe Brook was converted to the same system.

In 1907 the London & North Western Railway (L&NWR) obtained permission for a pair of extra tracks for suburban services beside their main line from Euston to Watford. Connection with the Bakerloo line at Queen's Park was planned with through running of Bakerloo line trains, so the new tracks were electrified using the 630 V DC four rail used on the Bakerloo. Delayed by the World War I, the first electric service ran in 1914 from Earl's Court to Willesden Junction, using borrowed District Railway trains. The L&NWR began running electric services from Broad Street to Watford in 1917 and from Euston in 1922. The first trains used electrical equipment from Siemens built in Germany, but the following ones used Swiss Oerlikon equipment. The units were 3-cars in length, formed from a driving motor car, trailer and a driving trailer.

From 1915 the London and South Western Railway introduced electric multiple units on suburban routes using a 660 V DC third rail system. Using converted steam-hauled carriages 3-car units ran with a trailer between two driving motor cars with Westinghouse electrical equipment. After 1920 two car trailer sets were used between these units to lengthen peak services to eight cars.

In 1921 new trains were introduced on the Underground's Piccadilly line in London with air-operated sliding doors. Between 1923 and 1934 Standard stock with air-operated doors replaced the gate stock on London's deep-level tube railways, improving access to the cars so reducing boarding times.

Grouping
In 1923 the main line railways in Britain were amalgamated (grouped) into four railway companies. South of London the Southern Railway took over route miles (24+1/2 mi) of railway electrified with overhead line at 6.7 kV, 57 route miles (57 mi) of railway electrified with a 3rd rail at 660 V DC, and the 1+1/2 mi long underground Waterloo & City Railway. The route mileage of 3rd rail electrification was to more than double in 1925 when the current was switched on the routes to Guildford, Dorking and Effingham and the route from Victoria and Holborn Viaduct to Orpington via Herne Hill and the Catford Loop. In 1926 electric trains started to run on the South Eastern Main Line route to Orpington and the three lines to Dartford using the 3rd rail system. In 1926 the Southern announced that the DC system was to replace the LB&SCR AC system, last AC train running on 29 September 1929. Including the London Bridge to East Croydon route electrified in 1928, by the end of 1929 the Southern operated over route miles (277+1/2 mi) of 3rd rail electrified track and in that year ran 17.8 million electric train miles.

For its suburban railways the Southern continued the L&SWR practice of running a three-car EMU off-peak and an unpowered two-car trailer between two three-car units during peak hours. Most of the EMUs were re-built by the Southern from locomotive hauled stock, mounted on new underframe and fitted with Westinghouse electrical equipment. In the 1930s electrication was extended to the main-line routes. Electric services started from Brighton to London Victoria and London Bridge on 1 January 1933.} For semi-fast services the 4Lav was designed; one composite coach had two toilets, one for first class and another for second class. For the fast services six-car units were developed with a pullman car or pantry in the set; three units had three first class trailers as well as the pulman car for peak hour London Bridge services. The Brighton Belle was an all pullman electric multiple unit, providing a 'at seat' meal service during the journey between London and Brighton.

In 1937 electric services began on the direct route to Portsmouth from Waterloo; the 4Cor was developed for this route. As well as gangways within units, connections between units were also available. These run with the similar 4Res units that had a restaurant car. On the Southern Railway suburban services, the lack of a driving position in the unpowered trailer was proving inflexible and in the early 1940s a four car unit was built. Classified as 4Sub, the 3-car units were gradually re-built into four-car units by adding a trailer, and new 4-car units were built from 1944 onwards.

In 1927 a Railway Electrification Committee, chaired by Sir John Pringle looked that the electrification of the railways and recommended either 750 V DC with a third rail or 1500 V DC with an overhead line. The Standardisation of Electrification Order 1932 set these systems, allowing 3000 V DC overhead line system in exceptional conditions. Work was started by the LNER electricifying the Liverpool Street to Shenfield, and the Wath and Sheffield to Manchester railway with a 1500V DC overhead line system, but World War II suspended work. On 11 May 1931, the LMS and LNER jointly opened the Manchester, South Junction and Altrincham Railway with an 1500 V DC overhead system, with Altrincham Electrics multiple units. These were 3-car all compartment trains with carriage similar to the suburban LMS stock.

In London, the formation of the London Passenger Transport Board in 1933 was followed by the 1935–40 New Works Programme. For sub-surface lines this involved an investment in rolling stock. For the new Metropolitan line the T Stock standardised the newer compartment stock Metropolitan Railway electric multiple units; The older wooden bodied stock, with hand operated sliding doors, was replaced by new O Stock and P Stock trains. These had air-operated sliding doors and used a new control system, the metadyne, and electric braking. In 1938 Q Stock was built by replacing the District line electric multiple units wooden trailers with new steel ones and equipping the trains with air-operated sliding doors and electro-pneumatic brakes. Also in 1938 the tube standard stock was replaced by 1,121 new cars of 1938 Stock with the control equipment under the car floor, thus giving 14% more capacity.

Outside London and the Southeast, in 1935 cable system that had been used on the Glasgow Subway since 1896 was changed to electric system with a third rail at 600 V DC. In 1938 the Wirral Railway was electrified with a 3rd railway DC system to allow through running on the still independent Mersey Railway, and units that would be classified Class 503 were introduced with air-operated sliding doors. Similar units (to be classified later Class 502) replaced older units on the Liverpool to Southport routes from 1940 to 1943. In 1938 the Tyneside Electrics 3rd rail DC system was extended to South Shields and the LNER electric units bought to allow for service expansion.

Post war reconstruction
The railways were placed under Government control two days before war was declared on 3 September 1939. After the war the railways were in poor financial state with a backlog of maintenance. Government control was not relinquished before the Transport Act 1947 nationalised most of the railways in the United Kingdom and control passed to the Railway Executive of the British Transport Commission. Some pre-war capital investment schemes that had stopped upon the outbreak of hostilities were restarted, such as 1500 V DC electrification over the Manchester–Sheffield–Wath route and on the Great Eastern suburban railways. The London to Shenfield route opened first in 1949 with what was to become Class 306 with 3-car units; these had air-operated doors and collected traction current with a single diamond-shaped pantograph. Similar electric multiple units entered service on the Manchester–Sheffield–Wath route in 1954. In 1954 what was to become Class 307, compartment stock with manual hinged doors, was introduced on the London to Southend route.

In 1948 a further report into the electrification system was commissioned, and this repeated the recommendations of the 1932 report in recommending either third rail at 750V DC in Southern England or an overhead line at 1500 V DC elsewhere. However an experiment was authorised in AC overhead line, energised at at 6.6 kV 50 Hz on the Lancaster - Morecombe - Heysham line. By 1954 similar experiments had been carried out in France on the Aix-les-Bains line with an overhead line at 25 kV 50 Hz, and both were considered a success. The report concluded that future electrification should be done with overhead line at 25 kV 50 Hz, except for the Southern Region tracks as there was extensive third rail electrification already in place. The Manchester and Crewe line was to be the first to be electrified at 25 kV 50 Hz. The overhead line at 1500 V DC that was already in place was to be converted to a 6.6 kV 50 Hz system.

When electrification was installed the lower voltage was 6.25 kV. What was to become Class 304 were introduced on the Crewe to Manchester route; the similar Class 305 were built for the Great Eastern main line. The Class 504 1200 V DC units, replacing the older units on the Manchester - Bury looked similar. The 1500 V DC units operating out of Liverpool Street were converted to AC operation in 1959-60. In 1961 Class 308 were introduced on the London-Tilbury line and in the following year the Class 309 became the first 100 mph capable EMU on BR, introduced on routes to Clacton.

After World War II, to replace the hand operated sliding doors on London Underground, the introduction of the unpainted aluminium R Stock reused the newer Q Stock trailers purchased before the war. New pneumatic camshaft mechanism (PCM) control equipment and motors were fitted and the cars formed with new trailers. When, in the 1950s the metadynes on the O & P Stock became unreliable and needed replacement, PCM control equipment was used and the modified motor car became known as CO and CP stock respectively; trailers were classified COP Stock. For the deep-level tubes the unpainted aluminium 1959 stock was initially developed to replace pre-war designs, and entered service on the Piccadilly Line and later on the Central.

In the Southern Region, the 4Epb was first built at Eastleigh works in 1950 with electro-pneumatic brakes and automatic buckeye couplers. Accommodation was in saloons and compartments with hinged doors at every seat position. Bulleid-bodied, production switched the standard BR Mark 1 body in 1954 when 2-car units were built to lengthen trains to 10-cars on Kent suburban routes. In 1957 the Class 501, similar to the 4-EPBs being introduced on the Southern Region, was introduced on the LMS lines in north London, replacing the LNWR units.

1955 Modernisation Plan
Included in the 1955 Modernisation Plan was the electrification of the SR Kent coast lines. The Tonbridge to Hastings line was excluded because of the restricted loading gauge; the Ashford to Ore line was included in the plan but not electrified. The lines were electrified at 750 V DC and was to become Class 411 stock were built; some units contained a buffet car. These 4-car units were similar to the Southern Railway's Portsmouth line 4Cor units, but updated using the standard Mark 1 coach design with EPB brakes and an electro-pneumatic camshaft traction control system. The two motor cars each had a pair of 250 hp motors. There were gangways within units and between units when used in multiple. What was to become Class 414 – 2-car compartment stock with a lavatory for third class in one of the cars and another for first class – were built for the stopping services. For the boat trains motor Luggage Vans (MLV) were built, single cars with two 250 hp motors designed to work in multiple with Class 411. Powered from their batteries, these were also were able to work short distances on non-electrified sections.

In the mid 1960s to replace the ageing Southern Railway mainline units Class 421 and what was to become Class 423 units were built. These four-car units had similar traction equipment and bodies and could work in multiple with Class 414 and Class 411 units, although there was one motor car with four motors. Class 423 were the semi fast stock, with high density 3+2 seating and a door to each seating bay; the Class 421 units were the express units with doors at the ends and middle. When introduced some express units had buffet cars.

In 1967 Southern Region wished to replace steam trains west of Bournemouth, could not justify electrification to Weymouth, but wished to retain through carriages. The Class 432 was a high power unit and between London and Bournemouth this was attached to one or two Class 438, trailer units with driving cabs. At Bournemouth the 4REP was detached and a British Rail Class 33 locomotive, adapted for push-pull working was attached country end. This hauled one or two trailer units to Weymouth and pushed them back.

In 1965 the railway on the Isle of Wight needed replacement rolling stock, but it had a restricted loading gauge. At the time London Transport had some surplus standard tube stock and British Railway bought fifty-five cars. At first it was intended to fit bus engines, but the line was electrified with the 3rd rail DC system and the cars overhauled and formed into 3 and 4-car units. These ran from 1967, until replaced in 1989-90 with 1938 tube stock, formed into 2-car units.

A small number of units were design around the Mark 2 coach. In 1966 what was to become Class 310) began operating on commuter services from London Euston and in the West Midlands. The Class 312 were similar units introduced in the mid-1970s.

In the early 1960s the extension of the DC electrification of the Metropolitan line as far as Amersham saw the introduction of A Stock sub-surface stock. These 4-car units had PCM control equipment; trains were normally 8-car in length, formed with two units. These replaced the earlier F Stock, T Stock and the electric and steam locomotive hauled stock. In the early 1970s 6-car C Stock was introduced on the Hammersmith & City and Circle lines and in late 1970s the 7-car D Stock and another batch of C Stock replaced the Q, CO and CP stock. The new deep-level Victoria line was built and with the 1967 Stock introduced automatic operation in 1968. The Jubilee line opened in 1979 with the 1972 tube stock. One person operation (OPO) was introduced over the London Underground after agreement was reached with the unions with the Hammersmith & City line in 1984, but on the Central and Northern lines this required new trains, delivered in the 1990s.

In the late sixties British Railways adopted the Total Operations Processing System (TOPS) to manage their rolling stock. Electric multiple units were given six digit unit numbers, the first three digits representing the class and the last three being a unique identifier. AC electric multiple units class numbers begin with a '3', Southern Region 3rd rail DC electric multiple units with a '4' and other DC electric multple units with a '5'.

In the late sixties the need for a new British Rail design was recognised. Prototypes of the British Rail New Generation, 1972 or PEP design were built and placed in passenger service in 1971. Constructed from aluminium with all vehicles powered and rheostatic braking, the production units were built by BREL at York Works with two sets of air-operated doors on the sides of the car and fully automatic tightlock couplers. The first units were the dual voltage Class 313 built between February 1976 and April 1977 for the routes out of Moorgate via Finsbury Park. Class 507 DC units were built in two batches from 1978 to 1980 and the similar Class 508 units in 1979-80. After temporary use on the Southern Region, these replaced units in Merseyrail. AC units also followed: Class 314 in 1979 and Class 315 from 1980 to 1981. In mid 1990s new trains were introduced on the London Underground's Northern line and Jubilee lines with regenerative braking and allowing the withdrawal of guards.

Mark 3 coach design
Other units were based on the all-steel Mark 3 coach design. Most are 20 m long, with two pairs of air-operated doors on each side of the coaches and built at BREL York. The first to be introduced were the AC Class 317, built in two batches, from 1981–82 and 1985-87 with thyristor control systems. The DC Class 455 for inner-suburban duties in South London were built in the early and mid-1980s with recovered traction motors and equipment. The Class 318 were built by BREL for Scotland in 1985–86. The Thameslink route across London needed dual voltage units that could change from AC to DC at Farringdon. The Class 319 were built in two batches in 1987–88 and 1990 with gate turn-off thyristor control systems. The Class 442 were built in 1988 on the for the DC electrified South Western Main Line from London Waterloo to Southampton Central, Bournemouth, Poole and Weymouth. These 23 m long units have air-operated plug doors at the vehicle ends, and fitted with air-conditioning. Twenty-four of these 5-car units were built in 1988-89 by BREL at its Derby works, using traction equipment from the 4Reps they replaced. The AC Class 321 were built in three batches from 1988–91 by BREL, with  Class 322 and the 3-car Class 320.

The 2-car DC Class 456 units were built by BREL at York Works from 1990-91 to work with the Class 455s.

In 1979 testing started on the West Coast main line of the Advanced Passenger Train (APT), trains being made from two Class 370 units composed of a driving trailer, five trailers and a power car. To increase speed over the conventional track the car bodies tilted, however problems meant the trains were withdrawn. The tilt technology was used twenty years later in the Class 390 units on the same route.

In the 1980s, prototype tube train designs were trialled in order to generate feedback about future developments. These led to the 1992 tube stock that replaced the ageing 59/62 stock on the Central line. The extension of the Jubilee line also saw the introduction of the externally similar 96 tube stock; refurbishment of the 83 stock was been considered, but building new trains cost about the same.

In 1980 the Tyne and Wear Metro opened over the Tyneside Electrics route diverted through tunnels on parts of the line. New trains were introduced based on the German Stadtbahnwagen B light rail units and power was taken from an overhead line at 1500 V DC. In London the Docklands Light Railway in 1987 opened with automated light rail units; trains are staffed by a train captain who can drive the train in abnormal situations.

In the 1980s and 1990s Network South East developed the Networker trains, with micro-processor controlled three-phase AC traction motors on half the axles. The build of the first Class 465 units was split between the newly privatised BREL and GEC-Alstholm.

Eurostar trains were ordered in 1989 to run from London to Paris and Brussels through the Channel Tunnel, then being built. The high speed trains were designed to run over the DC electrified southern British network, through the AC electrified Channel Tunnel, on the French high speed railway network (LGV Nord) at 300 km/h and Belgium railways. Similar to the French TGV but built the British loading gauge, the trains are 20 coaches long with two power cars and the bogie on the passenger cars next to the power cars motored. The trains entered service in 1994.

Privatisation
Train Manufacturer BREL was privatised in 1989, and between 1994 and 1997 the rest of British Rail was privatised. Ownership of the track and infrastructure passed to Railtrack on 1 April 1994; afterwards passenger operations were franchised to individual private-sector operators and the freight services sold outright. Rolling stock is owned by ROSCOs and leased to the train operators; competitive tenders are invited from manufacturers for new trains. To ensure flexibity with leasing arrangements electric multiple units are specified to be able to be modified to run on both the 25 kV AC and 750 V DC systems. Most DC units do not have the transformers and pantographs fitted, but some (such as the Class 377) have sub-classes that operate on routes requiring a switch between AC and DC operation en route.

The first Bombardier Electrostar units were the AC Class 357, built in 1999–2001 for c2c and these were followed by the DC Class 375 built in 2001-04 for Connex South Eastern and Connex South Central. In 1999 the UK Health and Safety Executive issued safety regulation requiring the withdrawal all rolling stock without override protection by 1 January 2003 and with slam doors by 1 January 2005. Mark 1 coaches and multiple units based on the design did not comply with either requirement and needed replacement or modification. However, Connex lost both franchises, and when Govia took over the South Central franchise as Southern they modified their specification and their units became Class 377, although the only major difference today is the Southern units have a camera on the side of every car linked to screens in the driver's cab. Introduction was protracted on both routes with problems such as cab and control equipment so the HSE extended the use of Mark 1 based rolling stock until 31 December 2004 with the proviso: "... that any Mark 1 rolling stock operated by the TOCs after 31 March 2003 must form part of a train fully fitted with a train protection system." It was 2005 before all units and entered service. To increase Southeastern suburban stock the DC Class 376 was delivered in 2004-05. Dual voltage Class 378 units were delivered for London Overground from 2007; the AC Class 379 for National Express East Anglia and some more 5-car Class 377s are on order for Southern.

To improve services and replace some of the older trains in 1998 South West Trains ordered 30 x 4-car Juniper Class 458 DC units; in 1999 similar Class 334 3-car AC units started run in Scotland. The DC units were assembled with 8-car Class 460 units ordered to replace the push-pull trains used on Gatwick Express services. However, the Juniper units had a protracted entry into service; the Class 458 units had poor reliability so it was 2004 before all units were in service and with this continuing plans were made in 2005 to withdraw the units from service, although reliability has since improved. for operational reasons the Class 460 units have been withdrawn and it planned the coaches will be used to extend the Class 458 to 5-car units.

In 2000 Siemens Transportation supplied the Class 332 for the Heathrow Express in 1998 and the similar Class 333 for the West Yorkshire PTE. When South West Trains needed to replace their Mark 1 stock in 2001, after the problems with the Juniper Class 458 units, the units chosen were from the Desiro UK range. The 23 m Class 444 was introduced for main-lines services to Portsmouth and Bournemouth and the Class 450 for the outer suburban services. AC versions have entered service elsewhere: the Class 350 for stopping services on the West Coast Main Line and the Class 360 for outer suburban Liverpool Street services. Similar Class 380 3 and 4-car AC units were built for the Strathclyde area in 2009–10.

From 2000 to 2005 Virgin Trains modernised the West Coast main line with Alstom's Class 390 125 mph capable 9-car units. These use the tilt technology developed twenty years previously by the APT project. These units were designed for speeds of 140 mph, however speeds over 125 mph require in-cab signalling and this has not been installed. some units are being lengthened to 11-cars, doubling the standard class seats.

In December 2003 formal approval was given to run domestic services on the planned Channel Tunnel Rail Link (CTRL) (now High Speed 1) from Kent. In October 2004 Hitachi was announced to be the preferred bidder to supply high speed trains for these services. Preview services began in June 2009, a full regular service starting on 13 December 2009. The Class 395 6-car trains are dual voltage, capable of running on High Speed 1 at 225 km/h and on the classic DC lines at 160 km/h.

In 2011 new trains were introduced on London Underground's Victoria line with IGBT driven AC asynchronous electric motors and regenerative braking. S Stock is being introduced on London Underground sub-surface lines in 8-car sets for the Metropolitan line and 7-car sets for the Circle, District and City and Hammersmith lines. Also with IGBT driven AC asynchronous electric motors and regenerative braking these units have every axle motored and are capable of running from 750 V DC. The first air-conditioned London Underground units there is a wide gangway the length of the train. It is planned that an automatic train operation system will be installed in 2018.

Planned trains
two thirds of the rail passenger cars used on Network Rail is part of an electric multiple unit. Of these 32% are capable of 75 mph, 62% 90 or 100 mph and the remaining 7% 125 mph. The most common unit length is four cars, but this can vary from 2-car to 9-car, and some Class 390s are currently being lengthened to increase formations to 11-car. Cars are 20 m or 23 m long. Seating capacity depends on the intended use of the train; for example inner suburban units have lower number of seats giving more room, especially around the doors, for standing passengers and allow access, whereas an interurban high speed train would have comfortable seats.

a quarter of the railway track in Great Britain is electrified with overhead line and 14% with third rail. Third rail electrification is increasing seen as outdated and inefficient, although the rolling stock can be cheaper and the clearances needed reduced. Overhead electrification at 25 kV 50 Hz is cheaper to install and operate, more energy efficient, operates better after snowfall and allows more power to be delivered to the train. An economic case can be made for replacing DC electrification with AC when the trackside equipment reaches the end of its life, as long as the rolling stock is capable of conversion and costly infrastructure works are not needed. Some lines, such as the Merseyrail tunnels in Liverpool and the Thames Tunnel in the East London Railway may not be suitable for conversion. As London's suburban trains such the Networker and the Class 455 are not suitable are conversion but the outer-suburban Desiro and Electrostar are, conversion of the outer suburban lines with trains changing mode en route is considered the best option. The third rail electrification between Basingstoke and Weymouth needs renewal in the next ten years. In the 2012 High Level Output Specification the Department of Transport has asked the rail industry to present plans to convert the line from Basingstoke to Southampton Docks by 2019 as part of a new electrified route from North to South and as pilot conversion project.

On order, to be delivered by 2015, are twenty Class 350s being bought by London Midland, although ten are to be transferred to Transpennine Express for Manchester Airport to Scotland services. Southern are buying thirty-four 5-car Class 377s, 26 to lengthen services in south London, and 8 dual voltage. Eurostar have ten Siemens Eurostar_e320 sets on order due by the end of 2014. To provide new trains for the Thameslink Programme, a consortium including Siemens Project Ventures GmbH, is named preferred bidder and entry into service is currently scheduled from 2015 to 2018. Similar Crossrail electric multiple units, given TOPS Class 345, are planned to enter service in 2018. For Intercity Express Programme bi-mode trains are planned to enter service on the Great Western main line from 2017, after electrification of the Great Western Main Line. Further trains on the East Coast route to Scotland are due from 2018. A 2013 long term rolling stock strategy considered that because of the planned electrification programme, predicted growth in rail travel and the need to replace vehicles as they reach the end of their lives between 13–19 thousand electric cars will need to be built by 2043.