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1992 tube stock

“I don’t want to testbed anything else, ever.” — Geoff Thackwray, then General Manager, Central Line

“The Central Line now works almost as well as it did in the days before they spent £800m on it” — Andrew Martin, ‘Tube Talk’

This page was last updated on 28 August 2017
with selected modifications to 27 November 2023

The 1992 tube stock forms the Central Line fleet, and also that of the Waterloo & City Line. It is technologically advanced for its time and carries many innovations.

Above: A Central Line train of 1992 tube stock approaches Loughton with a westbound service on 9 April 2015 at 1518hrs.

History

The design of the 1992 tube stock was finalised following extensive testing involving three prototype trains being built by three different manufacturers.

Drawings for the three prototype trains, designated 1986 tube stock, were produced by DCA Design of Warwick under the leadership of Design Chief David Carter, working for LUL and with Metro-Cammell and BREL.

The prototypes were each given distinct colours (red, blue and green) to assist passengers in identifying them for the purpose of public reactions and feedback. A further public-opinion exercise was conducted at Stratford station which focussed on the interior, including the moquette.

The production version was built by ABB Transportation Ltd, who used to be BREL at Derby, and who subsequently became ADtranz but who were bought by Bombardier Transportation in 2001.

Description

Trains of 1992 tube stock are formed from 2-car units. All trains in passenger service must contain at least 2 units, in order to have a cab at each end. Trains on the Waterloo & City line (and, as at July 2019, shuttle services between Woodford and Hainault at some time in the future) are 2-unit trains (i.e. 4 cars long), while the vast majority of Central line trains are run as 8-car trains (i.e. comprising 4 units).

This stock features extra-wide doorways with externally-hung doors (a first on LU), very large side windows not seen on any other tube stock to date, and Digital Voice Announcements from new. It also incorporates Track-to-Train CCTV which shows the driver a view of the platform, even after the train has started to leave the station. Every axle is fitted with a traction motor (type LT130 DC), which improves adhesion; and braking can be done using tread friction brakes, regenerative, or rheostatic braking — or a combination of the three.

Above: The 1992 stock has a distinctive shape, seen to advantage in this view taken in Ruislip depot on 1 May 1999.

Each unit of the stock comprises two permanently-coupled cars which share compressor, shoegear and thyristor traction equipment, amongst other things. Half of the units have a cab at one end (A-B units); of those units having no cab (B-C units), some are equipped with de-icing facilities (B-D units). Every end of a unit not having a cab is fitted with shunting controls. The automatic couplers used on the outer faces of each unit are completely reversible: either end of any unit can be coupled to any other, greatly simplifying marshalling operations in depots and lessening the severity of the Depot Duty Manager (DDM)’s headaches!

This stock was intended to be a testbed for modern Automatic Train Operation systems on the Underground, and was the first on LU to make heavy use of computer technology; there is a great deal to go wrong on these trains, and in the early days it did so.

A lot.

The trains may be bristling with [what was then] the latest technology, and be capable of self-diagnosis of all ailments, but if they refuse to go from A to B at normal speeds then the train service falls apart. Very many modifications have been made to the stock during the early phase of its life, in an effort to overcome these difficulties. Andrew Martin, who had a column entitled Tube Talk in the Evening Standard magazine, wrote of the 1992 stock with some justification that “The Central Line now works almost as well as it did in the days before they spent £800m on it”.

At around 8 o’clock in the sunny summer morning of 2 August 1998, an eastbound Central Line train for central London and Epping runs across the complex pointwork and into White City platform, where right-hand running is in force. Careful examination shows that the driver is running with the nearside (‘N’) cab door open; this is not possible when the train is in ATO mode.

The interior of a westbound train a few minutes later on the Ealing Broadway branch, at West Acton: the grab-rails have been painted to match the line colour, a feature not carried through to the new Northern Line trains (!). The stock was originally fitted with armrests (or “personal space dividers”) between seats, but these were soon forcibly removed by vandals: however, the armrests are still present on the Waterloo & City Line trains.

This image incorporates a view of the 1992 stock’s original moquette, a grid of repeating patterns on a red base, which was designed by Jonathan Sothcott. This moquette was replaced by a blueish non-line-specific design when the saloon interiors were refreshed.

Waterloo & City Line

As well as the whole fleet of 8-car 1992 stock Central Line trains, which displaced the 1962 stock, a further five four-car trains of 1992 stock were ordered to replace the life-expired 1940 third-rail electric trains on the Waterloo & City Line. As far as I have been able to determine, the original specification for these trains was no different to that of the Central Line, except for the paintwork being Network SouthEast and not LU corporate livery (the W&C Line was not owned by LU until 1994): however, repeated modifications to the main Central Line fleet mean that the W&C Line stock is about 150 changes adrift of it. Amongst the obvious ones are that W&C stock retains tripcocks and does not use ATP/ATO, and did not need the High Performance or WSP upgrades; additionally, regenerative braking is disabled on the Waterloo & City Line fleet.

Beyond the platforms at Waterloo on the Waterloo & City Line is a small depot; this nominally contains 8 roads, but number 1 is non-existent, number 5 is used by all service trains for reversing to get into the departure platform from the arrival side, and number 8 is the access road: the only way for trains and larger materials to get into the line is by craning them in through the access hatch and down onto number 8 road. There used to be a hoist which lifted vehicles to the main-line tracks above, reached by a trailing junction to the west just after leaving Waterloo for Bank, but this was removed when the Eurostar terminal was constructed. The outside of the current access pit can be found at the foot of Spur Road, next to Lower Marsh on the south-east side of Waterloo main-line station.

The above picture was taken at the open day to mark 100 years of the Waterloo & City Railway, on Saturday 8 August 1998 (as the “Centennial Day” sticker on the ‘M’ door shows). One two-car unit has been jacked up to allow easier view and access to the underneath; it is in number 2 road, and we are looking towards the platforms of the station (there is a wall behind the photographer).

There were rumours abounding during much of 1999 that the Waterloo & City 1992 stock units were to be given to the Central Line to strengthen the latter’s fleet; the W&C would then be lumbered with tired-out 1972 MkI stock recently withdrawn from the Northern Line. At the time, sources close to the heart of Central Line management assured me that this “would never happen”: the enormous cost and the non-availability of spares required to modify the W&C stock would make it unfeasible, and also LUL would be taken to court by the City of London Corporation (who helped pay for the W&C Line’s new trains). By the end of 2000, however, this idea had come to life again and a project manager had been appointed too, giving the plan real substance for the first time. In addition, the line was transferred from Central Line to Bakerloo Line management (with the Bakerloo Line operating the similar 1972 MkII tube stock). The idea has long-since been dropped, just as predicted, and the line became grouped with the East London Line; with the latter’s then-impending re-assignation to the National Rail network, the Waterloo & City Line was re-transferred to Central Line Management on 9 December 2007.

During the summer of 2006 the Waterloo & City Line’s trains were removed from the line and taken to Doncaster for refurbishment. They returned in LUL corporate livery to a line whose track and signalling had been completely renewed. Views of the craning operation, and the refurbished trains, will eventually appear here.

Technical improvements

From September 1998 the Central Line ’92 stock fleet received a software upgrade, giving increased acceleration and braking rates, as well as increasing its maximum speed to 100km/h (62mph). In the bottom-left-hand corner of the driver’s windscreen, the white reverse-side of a sticker was visible, with the front side facing the driver saying “High performance operating” — however these have peeled off by now, and all units have been converted. Another modification, Wheel Slide Protection (WSP), was applied; unfortunately this was carried out after the High-performance upgrade, which meant that for a time the fleet had a serious problem of wheel-flats (where axles lock under heavy braking).

Bogies and underframes on the 1992 stock fleet were being overhauled in 2004.

Replacement (already!?)

In the spring of 2008, rumours began to circulate to the effect that LUL is seeking to replace the traction motors on these trains; this follows a never-ending list of problems with them & their gearboxes, including the Chancery Lane derailment. As new motors would be AC, all the traction equipment would need replacing; as the wiring, software, bogies and underframe-attachment points would all need extensive modification or replacement, it has been suggested that LUL might pursue the cheaper idea of simply replacing the trains altogether.

As of late 2013, the entire Central Line fleet has had its Kawasaki bogies replaced. As a result, from 9 November 2013 the ATO braking rate in tunnel sections, previously reduced in 1999 to 1.05 m/s/s, was restored to its design value of 1.15 m/s/s.

In February 2015, an article from the company’s internal progpaganda indicated that the 1992 stock is currently expected to last until it is replaced “between 2028 and 2032”.

Central Line Improvement Programme (CLIP)

On 25 August 2017 it was announced that the contract for replacing the DC traction equipment on the Central Line fleet had been awarded to Bombardier Transportation. The contract is worth £112.1m and lasts until 2024, and will see the fleet equipped with Bombardier’s Mitrac AC traction & control equipment as already found on the S stock. This project has been assigned the name CLIP, which stands for Central Line Improvement Programme, and it is taking place at Acton Works. Each train is receiving completely new traction equipment as above, plus a refreshed saloon interior including new moquette, customer information system and CCTV. One presumes that the Waterloo & City Line fleet will be left as it is, with its LT130 DC traction motors?

On Monday 24 November 2023 the first CLIP train operated in service, for the purpose of a press launch, on one round trip from Hainault to Woodford via Chigwell.

Automatic Train Protection/Operation

The 1990s modernisation programme for the Central Line included the complete re-signalling of the line to equip it for eventual Automatic Train Operation (ATO, in which the train drives itself). Fundamental to this is Automatic Train Protection (ATP, which tells the train and driver the state of the line ahead).

Re-signalling

Block marker boards were fitted to the trackside, and the track was equipped with code-generators that inject high-frequency coded signals into the running rails for the train to pick up and interpret. Since 1997, ATP (which, under manual driving, ensures that the driver obeys speed limits and signals) has been in use throughout the line. At this stage, most running signals and all trainstops became redundant and were removed.

Automatic Train Operation

Once ATP was working, a test train ran all over the Central Line under ATO during engineering hours for months, to allow any bugs to be ironed out of the system. However, progress with the widespread introduction of ATO dragged way behind schedule: this was because the trains could not be allowed to drive themselves until the Wheel Slide Protection had been fitted — there were too many problems associated with sliding past platform stopping-points and flatting yet more wheelsets.

In the last days of 1999, ATO started being used in passenger service. As of Monday 4 March 2002, ATO is used throughout all passenger-used parts of the Central Line. This follows the approval for ATO running on the final manual-only section of track, which was between West Acton and Ealing Broadway. ATO is normally used at all times. However, to “keep their hand in”, drivers should run in Full Speed Coded Manual in the open-air sections on Sundays; in addition, the Line Controller may ask specific trains (or all trains in a given area) to come out of ATO mode for various reasons including crowded platforms and slippery rails.

Running under ATO has not been without its difficulties; initially there were daily (if not hourly!) platform-overruns, mostly a result of slippery rail conditions during wet weather at outdoor locations such as Stratford and Leyton. However, by February 2002 the incidence of ATO overruns was down to one per week. The ATO provides quite a “lively” journey in some locations, with approaches to some stations being at speeds of 80kph (50mph)!

How it works

A full explanation of Automatic Train Protection/Operation and how it all works, written by Clive Feather, can be found on his signalling pages. Although using updated versions of the technology, ATO is not new: the Victoria Line has been running under ATO throughout its life — see the 1967 stock page for more.

Chancery Lane derailment

In the early afternoon of Saturday 25 January 2003, a westbound Central Line train derailed as it entered Chancery Lane station. The rear five bogies left the track, and the rear three cars suffered moderate damage after colliding with the tunnel walls and the platform edge; fortunately passenger injuries were light, the worst being a broken ankle sustained whilst attempting to jump out of the train to the platform between cars. The cause of the derailment was quickly established to be because of a traction motor falling from a bogie onto the track and being struck by the remainder of the train passing over it. This was not the first such derailment, though the previous ones had been in/near depots and at low speed.

Because the safety of the trains could not be assured, the entire 1992 tube-stock fleet was halted the same afternoon, and a massive programme of modifications was put in hand: this involved the fitting of some 11,200 new traction-motor bolts(1), and also secondary brackets intended to catch a loose motor before it could do much damage. The Central and Waterloo & City Lines were completely closed for several weeks, the former re-opening in stages from 14 March (Leytonstone – Bethnal Green) to 12 April (full service) as modified trains became available.

A finger of suspicion has been pointed at the Automatic Driver system of these trains, which will “slam” from full motoring to full braking in a manner that most human drivers wouldn’t do; perhaps this accelerated the fatigue of various parts of the drivetrain and its mountings. The design of the original Kawasaki bogies and the way that the traction motor was fixed to them has also been criticised. As at August 2005, the 1992 stock may not exceed 85kph, whereas it used to be allowed to 100kph.

In the driving cab

This view, taken at rail level in Ruislip Depot on 1 May 1999, shows the modern cab interior of this stock-type; the A car of A-B unit 91109 is the vehicle in question. At the far left of the shot is a fold-out seat for an instructor, and the desk in front of him (extreme right) has been lifted up to allow access to equipment beneath it. The back-rest of the driver’s seat has been folded down and is partly obscured by the controller-column which is fixed to the floor. A quick rundown of the main visible features follows:

The Traction Brake Controller (TBC), to give it its full name, is the red handle seen poking forward from the armrest on the driver’s right-hand side. Its upper section forms the Deadman device: the driver holds the black hand-grip and swivels the head 75 degrees either way about a vertical axis; if he lets go, it springs back to the position shown and the emergency brakes are applied.

The thicker red-painted arm of the TBC comes forwards out of the armrest by about six inches, with the driver sliding his forearm over the shiny top surface of the pedestal. The controller can be pushed fully forwards to the end-stop for full power, retracting it to a notch half-way back is coasting, further back is full braking: a heavy click puts it into the “stowed” position as seen.

The console in front of the driver contains an emergency brake button and whistle control (the red and orange buttons at the top, respectively); twin door-control panels (left-hand one visible just to the right of the TBC); the monitor for platform-to-train CCTV (black rectangle beneath the right-hand orange button); another panel (further to the right) with clock, countdown marker, door open lights, other ATO-related features. Above this, directly ahead of the driver and below the windscreen, is the backlit-LCD dual display for Current Speed and Target Speed (green and orange respectively): these are of horizontal bar-chart type, extending from zero on the left to 100kph on the right.

The small oblong window seen above the console is so that the driver can see the stopping-point marker (green/yellow/black board fixed to the tunnel wall or to railings on the platform). Tube stocks of 1967 to 1973 vintage had wrap-around windows, while their predecessors had such small cabs that the cab-door windows sufficed: sadly it has become necessary to specify missile-proof glass for cab windows now, and this is not available in wrap-around form.

The large panel next to that small window contains controls for the cab environment and doors, Mayday button, ATP Emergency Alarm, PA and Train Radio, to name but a few; a telephone handset for the last two is obscured by the chair. Above it is a smaller panel for issuing manual commands to Sonia, the DVA: however, routine announcements are triggered automatically by the destination indicator control panel (on the right-hand console) and the ATO system. Finally, the green notice fitted on the edge of the console, near the footrest, carries pictographic and English instructions for deploying the emergency detrainment system — on this stock it is a ramp which is stowed upright as part of the ‘J’ door.

Sonia

The 1992 stock carried the first widespread implementation of a Digital Voice Announcer (DVA) on the Underground, and quickly became known as Sonia to traincrews; this was because having a somewhat repetitive announcement in your ear once a minute “getS ON YA nerves”! However this DVA was (in my opinion) the best they had for several years. The dulcet tones (which can be heard on my sound-effects page) were those of Janet Mayo who works for BBC Television in Nottingham; she has been in touch with your editor. She writes,

“Perhaps you’d like to add an apology from me on your website to the members of the Central line staff who find my voice gets on their nerves — I am sorry — I may add I’ve had a lot of complimentary comments on the voice as well so hope I don’t put everyone off!”

I feel sure many readers will join me in responding that this nickname bears very little reference to the quality of the voice, and is largely due to the fact that you’re stuck listening to it all day, every day!

The soothing qualities of the Janet-Mayo DVA are now a thing of the past. In late 2003 a new version was introduced, which had been voiced to sound similar to its predecessor; it features the voice of Emma Clarke; the outdated references to “Network SouthEast Services” et cetera have been replaced with suitable alternatives.

Sandite unit

One unit, 92442-93442, is specially modified so that it can be used to spread Sandite to combat rail-adhesion problems during the leaf-fall season. When required, it used to run (out of service) between West Ruislip and Ealing Broadway via White City, formed between two A-B units as a 6-car train. The Sandite is carried in tanks which sit in the saloon.

When it isn’t the leaf-fall season, 92442-93442 can be found running in normal service. It can be recognised from inside the saloon by the circular aluminium plates screwed to the floor in a doorway: these cover the ends of the pipes which deliver the Sandite to the railhead.

Sandite duties on the eastern reaches of the Central Line are covered by the Wasser, and latterly (prior to 2012) a second train of 1962 tube stock—formed of 5 cars—has been converted for Sandite use on the western branches, presumably freeing up 92442-93442 for normal service.

Unusual destinations

The Central Line and Waterloo & City Line trains were all fitted with a destination/announcer system capable of working on both lines; this, and the closure of the Ongar branch, give rise to the possibility of setting up impossible destinations on the display.

This Central Line train is stabled in a siding adjacent to the terminal platforms at West Ruislip; whoever drove it there has “funnied” it by setting the headcode number to 999, and the destination reads Ongar. Unfortunately, the displays on these trains flickers at fairly low frequency (just visible to the human eye, so about 20 cycles per second), so a portion of the displays has come out blank on the photograph. (Note to self: use exposure times greater than 1/15th of a second where possible!). West Ruislip’s traincrew depot is visible at top right; the station has been thoroughly modernised since this photo was taken, including the rebuilding of the platform buildings and canopies.

There! With a decently long nighttime exposure, I caught this further example of a Central Line train being “funnied”, since the Central Line doesn’t call at Waterloo. The location is Ruislip depot car-sheds, whose illuminated inspection pit can be seen beneath the train; note also the TBC visible in the cab.

By coincidence, the above photo shows the same cab and unit as featured in the Driving Cab section, although on a different occasion; In late October 1999, unit 91109 was still there, somewhat dismantled and clearly long-term stopped; however it has since returned to traffic.

In the upper third of the left-hand cab windscreen is a white box; this is the reverse side of a VDU screen which is angled across the cab to face the driver. It is a display for the DTS (Data Transmission System), and provides all kinds of diagnostic information relating to the health of the train and the ATP/ATO. The DTS logs everything that happens to the train, and can in principle be downloaded each night at the depot (this takes over half an hour, and is only done upon request to gather data relating to an incident). Certain pieces of information (including operating-mode and percentage of passenger-loading) are transmitted in real time to the Central Line Control Centre.