British Rail Mark 3

British Rail's third design of standard passenger carriage, designated 'Mark 3' (also described as Mark III), was developed in response to growing competition from airlines and the motorcar in the 1960s. A variant of the Mk3 became the rolling stock for the High Speed Train or Inter-City 125,

Originally conceived as locomotive-hauled coaching stock, the first coaches built were for the prototype HST in 1972. Production coaches entered service between 1975 and 1988, and multiple-unit designs based on the Mark 3 bodyshell continued to be built until the early 1990s. The Mark 3 and its derivatives are widely recognised as a safe and reliable design, and most of the surviving fleet is still in revenue service on the British railway network in 2013.

Introduction
In the late 1960s British Rail had modernised its rolling-stock fleet on its key long-distance routes with the introduction of the air-conditioned Mark 2 coach, and was implementing extensive plans to alter track geometry and rework slow sections of track with the aim of decreasing journey times and improving passenger comfort; however, the railway continued to lose passengers to car and air. The "Inter-City" brand was created to show off these improvements, including the electrification of the West Coast Main Line (Glasgow, Preston, Manchester, Liverpool to London Euston) and new air-conditioned versions of Mk 2 coaches. Elsewhere the French, German and Italian railways were steadily electrifying their main routes and providing new, comfortable and smooth-running rolling stock, while in Japan the new purpose-built Tokaido line was opened with 125 mph air-conditioned rolling stock.

Under the chairmanship of Sir Stanley Raymond, it was decided to reduce journey times further on long-distance trains by increasing line speed to 125 mph where practical - the maximum considered possible on Britain's Victorian-age railway. At the end of 1968 proposals were submitted to the Commercial and Operating Departments of British Rail for a new fleet of third-generation standard coaching stock, designed to run at 125 mph.

The rapid development required for the Inter-City 125 High Speed Train (HST) in 1969 made the Mk 3 coach design the obvious choice for this train, and in 1972 the first Mk3 coaches were built; 10 for the prototype HST.

Construction
The Mark 3 looks similar to Mark 2D, 2E and 2F coaches, but is of a completely different design. A difference aiding quick recognition is the ridged roof of the Mark 3 and under-frame skirt compared with a smooth roof and visible below-frame equipment on the Mark 2.

The bodyshell is 75 ft long, almost 10 ft longer than the Mark 2, of full monocoque construction with an all-welded, mild steel, stressed skin, and has gained a reputation within the railway industry for its exceptional strength and crashworthiness. Another important advance over its predecessor was the adoption of secondary air suspension between the body and the bogies, giving an exceptionally smooth ride. The bogies, classified BT10, were designed specifically for the Mark 3 and have coil-spring primary suspension with hydraulic dampers, enabling a maximum speed of 125 mph &mdash; the Mark 2 is limited to 100 mph. Disc brakes in place of the Mark 2 design of clasp brakes completed the engineering package - enabling efficient deceleration from 125 mph and almost silent brake operation.

Ancillaries such as electrical and air-conditioning systems were grouped together in discrete modules housed behind an aerodynamic skirting between the bogies; on the Mark 2 these were mounted above and below the passenger seating area. The lighting and air-conditioning fittings were for the first time integrated into the ceiling panels. Other new features (first seen on the Mark 2F) were the pneumatically operated automatic gangway doors which were triggered by pressure pads under the floor. A speed-operated central door-locking system for the manually operated slam-doors was installed in the Mark 3 stock from 1993.

The main difference between the HST vehicles and the loco-hauled Mark 3A relate to electrical supply arrangements. HST Mark 3 coaches take an industrial voltage/frequency 3-phase supply directly from an auxiliary alternator in the power car to supply on-board equipment such as air conditioning. The loco-hauled vehicles take a standard single-phase 1000 V AC or DC train heat supply from the locomotive and convert it through motor generator units located under the floor. These convert the train supply to 3-phase 415/240 V 50 Hz AC to power air conditioning and other ancillaries. This makes the two types non-interconnectable in service conditions. The other main difference is the lack of buffers on HST coaches.

The later Mark 3B build provided additional 1st-class loco-hauled vehicles for the West Coast Main Line. These are virtually the same as earlier Mark 3As, but have an improved motor alternator unit with compound-wound motor, and seating derived from the Advanced Passenger Train (APT).

Prototype
10 coaches were constructed to run between a pair of Class 41 power cars as the prototype HST (prototype InterCity 125), exploring different seating and layout options for first- and second- class passengers, and evaluating different designs of catering facilities. In 1973 the prototype HST was evaluated during passenger operation in an 8-coach formation between power cars. The two spare coaches were rebuilt and redeployed into service in the Royal Train (coaches 2903 & 2904), where they remain in use today.

Main article: Prototype HST

Development
Initial plans for a large fleet of Mk3 loco-hauled coaches to run almost all Inter-City services were amended prior to construction to provide stock for the planned HST / InterCity 125 fleets, resulting in a much smaller fleet of Inter-City loco-hauled coaches for West Coast Main Line (WCML) services. Overall a much reduced number of coaches were manufactured, requiring many Mark 2D, 2E and 2F coaches to remain in front-line service.

The table below lists manufacturing variants as built, showing the quantity of each type/designation and original running numbers.

Key: See British Railway Coach Designations for details of the meaning of RSB, TRUK, BFO etc.

Usage


The Mark 3 design proved to be highly adaptable for use in BR's multiple-unit stock of the 1980s, with the following classes having Mark-3-based bodyshells:
 * AC EMU Classes
 * Class 317
 * Class 318
 * Class 319
 * Class 320
 * Class 321
 * Class 322
 * DC EMU Classes
 * Class 442
 * Class 455
 * Class 456
 * DMU Classes
 * Class 150
 * Class 210

The Mark 3 bodyshell was also used as the basis for Northern Ireland Railways' 450 Class DMU.

Since 1977, the Royal Train has used nine specially equipped Mark 3 coaches. Some of these were rebuilt from the original HST prototype vehicles.

Grand Central, an open-access operator on the ECML, uses HST sets on its services between London and Sunderland. The Mark 3 coaches were of the loco-hauled type, and had to have their couplers and electrical systems modified to make them compatible with Class 43 power cars.

Mark 3 coaches also still have a limited role on the WCML as sleeping cars on the overnight Caledonian Sleeper services between Scotland and London Euston.

The introduction of Virgin Trains' Pendolino electric multiple units on the WCML caused a large surplus of Mark 3 vehicles, which ended up in storage at Long Marston. Some former Virgin coaches were refurbished and cascaded to the Great Eastern Main Line, replacing Mark 2E/2F vehicles on London-Norwich services.

CrossCountry has reinstated HSTs on the CrossCountry franchise in response to criticism of the lack of seating capacity on the Voyager DEMUs used by previous incumbent Virgin Trains. To satisfy demand for these new HST sets, it is anticipated that more loco-hauled Mark 3 coaches will need to be converted for HST operation.

HSTs also continue to be used by First Great Western on the Great Western Main Line, by East Midlands Trains on the Midland Main Line, and byEast Coast on the East Coast Main Line.

Virgin has retained at least one complete Mark 3 set with a Class 90 locomotive -- initially used to cover peak-time Euston-Birmingham services while the Pendolinos underwent modifications, but it is now covering the loss of 390033 which was written off after the Grayrigg derailment in 2007. In July 2009, Virgin refurbished this set -- repainted into the Pendolino silver/black livery to bring it in line with the newer fleet, with the interiors receiving power sockets at every seat, the addition of WiFi, and new seat covers and carpets in the same style as the Pendolino and Voyager fleets, but the BR vintage seats and interior fittings remain. This set is nicknamed the "Pretendolino".

In January 2007, the first of the refurbished Mark 3 sets for the ECML were unveiled by previous franchisee GNER. These have been internally refitted to the same standard as the "Mallard" Mark 4 stock with the same styles of seating and lighting. The new Mark 3 Mallards were converted by Wabtec in Doncaster, and the final refurbished set entered service in October 2009.

Cargo-D, a rolling-stock logistics company, acquired 18 ex-Virgin West Coast Mark 3 coaches and repainted them in their original British Rail blue/grey livery and Inter-City branding -- the first time this had been seen since the late 1980s. The stock was used primarily for the company's own "Rail-Blue" charter operation and on lease to the now-defunct Wrexham & Shropshire (see below). Cargo-D went into administration in October 2011.

Wrexham & Shropshire, an open-access operator, introduced four of its own rakes of refurbished Mark 3 coaches hauled by a Class 67 locomotive for its services between London and Wrexham. After the collapse of Wrexham & Shropshire, these rakes are now used on Chiltern Railways services between London Marylebone and Birmingham Moor Street. Chiltern is now in the process of acquiring more Mark 3 coaches.

These developments will ensure that the vast majority of the Mark 3 fleet will be back in revenue service, reducing the possibility that a large number of the coaches may end up exported or scrapped. As a result of British Rail's over-provision of stock for sleeper services now long withdrawn, two-thirds of the Mark 3 sleeping-car fleet were either stored or scrapped.

Original formation
The original Mk3 coaches delivered as part of HST sets for Western Region (Class 253) contained Trailer First (TF), Trailer Second (TS), and Trailer Buffet Second (TRSB) variants in formation TF-TF-TRUK-TS-TRSB-TS-TS. Complaints from train guards about engine noise in the guards' compartments in the power cars led to an additional variant, the Trailer Guard Second (TGS) in 1980, based on the TS but with the end vestibule and one seating bay replaced by a guard's compartment. This replaced the last TS in all sets from 1980 onwards. Sets delivered for Eastern Region (Class 254) contained 8 coaches, originally in formation TF-TF-TRUK-TS-TS-TRSB-TS-TS. The TRUK cars were quickly replaced by a TS on the Western Region and most had been replaced on the Eastern Region by 1985 (many later rebuilt into loco-hauled buffet cars). TRUB cars (Trailer Restaurant Unclassified Buffet) were newly built from 1978, to replace the TRUK cars, and these were reclassified as TRFB (Trailer Restaurant First Buffet) from 1985 on the Eastern and Midland Regions and from 1989/90 on the Western Region.

Previous formations
Virgin Trains frequently operated HST sets in shortened formations between 2001 and 2004, the most common being five-car sets. This gave the trains better acceleration, so as to be similar to the Voyager units.

Current formations
Most operators of HST sets form them in eight-car sets, with East Coast operating nine-car sets, with an additional standard-class vehicle. The exceptions are CrossCountry, which operates seven-car sets with only one first-class car and a simplified buffet car; First Great Western, which operates some seven-car "high-density" sets with micro buffets and with more seats in each car on express services to Oxford; and Grand Central, which operates its HSTs as five-car and occasionally six-car trains.

Hauled stock
Mark 3A coaches were deployed on WCML expresses out of Euston to bring the three main long-distance routes from London up to the same standard. Initial variants were Second Open (TSO) and Open First (FO). Catering and sleeper vehicles continued to be Mark 1 stock until the introduction of Restaurant Buffet (RUB) vehicles in 1979-80, and the sleeper (SLEP) vehicles in 1981-82. In 1988 the process was completed with the elimination of Mk 1 parcels vehicles and their replacement by Mk 3-derived Driving Van Trailers, making the WCML push-pull.

Scottish Region push-pull services were initially made up of four TSO and one FO Mark 3A coaches with a Mark 2F DBSO. This was later changed when the FO was converted to a CO by the declassification of half a coach and installation of a partition between the two classes. An SO was removed from the formation. These vehicles were removed from the Scottish regional routes in 1989 when they were replaced with Class 158 multiple-unit stock.

Entertainment carriages
In 2009 First Great Western introduced 'entertainment carriages' fitted with at-seat television screens known as Volo TV. The system, which FGW claims is a "world first", is usually fitted to D-coach standard-class carriages. The service, originally charged for, is now free, but users have to provide their own headphones (standard 3.5mm stereo mini-jack plug) or purchase a pair from the cafe for £1.50.

In addition to radio and video feeds, a GPS train-location screen is provided allowing passengers to check the progress of their journey in real time. Externally an aerial has been fitted to the roof of these coaches.

Multiple units based on the Mark 3
The Mark 3 formed the basis of BR's Second Generation multiple unit fleet, introduced from the early 1980s onwards.

Electric multiple units include the 25 kV AC EMUs of the Class 317 and Class 318, and the 750 V DC EMUs of the Class 455 and Class 442. Also with a dual-voltage EMU which is the Class 319. Diesel multiple units include the short-lived diesel electric Class 210, and the diesel-mechanical "Sprinters" of the Class 150. The cars for Classes 150, 210, 317, 318 and 455 units are built on 20 m frames, and are outwardly similar. However, those for Class 442 are on 23 m frames, and visually look very similar to the familiar HST mark 3 coach. The main visual difference is the use of swing plug automatic doors rather than the traditional "slam-door" as used on HST stock. The Class 153 and Class 155, while of the "Sprinter family", are in fact built by British Leyland and have nothing to do with the Mk 3 carriage. This is also true of the Class 156, built by Metro-Cammell. The final batch of "Sprinters" of Class 158 (some rebuilt as Class 159) are of a design intermediate between that of the Mk 3 and the later Mk 4. In addition, a fleet of nine 450 Class DMUs were built at Derby for Northern Ireland Railways using Mark 3 bodyshells and Mark 1 underframes, together with refurbished power units and traction motors, recovered from the former UTA 70 class units. The last Mark-3-based EMUs built are the Class 321 and 322 units.

The Mark 3 in Ireland
The Republic of Ireland's national rail operator, Iarnród Éireann, ordered a fleet of Mark 3 carriages built between 1984 and 1989, with bogies to fit the Irish gauge of 1600 mm (5 ft 3 in). The fleet consisted of 124 Mark 3 and nine Mark 3A internationals which worked only the Dublin-Galway service, branded "C&uacute; na Mara" or "Hound of the Seas" as it was a coast-to-coast route.

Throughout the 1990s and 2000s, they were the backbone of the intercity rolling stock on the Irish railway network.

All of these coaches were built with automatic plug doors, which initially caused some concern as additional time and resources were required to perfect them. The design of these doors was later used on the Class 442 "Wessex Electrics". Most of the fleet was air-conditioned, except for a small number of coaches built originally as outer-suburban stock which ran in push-pull configuration. A number of coaches were first class, and there were several dining cars as well as five driving van trailers (DVTs) which included passenger seating. There were also a number of accompanying generator vans for supplying power.

In 2006/7, new carriages built by CAF of Spain (referred to in Ireland as Mark 4 stock) were introduced on the important Dublin-Cork route. The displaced Mark 3 coaches were then cascaded to other intercity routes.

However, in 2008 Iarnród Éireann began taking delivery of Korean-built 22000 Class railcars, which ultimately led to withdrawal of all Mark 3 coaches. The type's final service was a Dublin-Cork relief train on 21 September 2009.

Post-withdrawal in 2009 a number of efforts were made to sell some or all of the 130 carriages in the Iarnród Éireann inventory but some are still stored in various locations.