London Underground 1996 Stock

1996 Stock
In service 1997 - present
Manufacturer GEC Alsthom-Metro Cammell
(now Alstom)[1]
Replaced 1983 stock
Number built 441 cars[2]
Formation 7 cars per trainset[2]
Capacity 875 per trainset[2]
Line(s) served Jubilee
Specifications
Car length 17.77 m (58 ft 4 in)
Width 2.630 m (8 ft 7.5 in)
Height 2.875 m (9 ft 5.2 in)
Maximum speed 100 km/h (62 mph)
Weight Driving Motor: 30.0 tonnes (29.5 long tons; 33.1 short tons)
UNDM 27.1 t (26.7 long tons; 29.9 short tons)
Trailer: 20.9 t (20.6 long tons; 23.0 short tons)
Traction system GTO thyristor
(GEC Alsthom)[2]
Traction motors three-phase AC induction motor
(GEC Alsthom)[1][2]
Seating 234 per trainset[2]
Stock type Deep-level tube
Notes
London Transport portal

The London Underground 1996 stock is used on the Jubilee line of the London Underground. It was built by GEC Alsthom-Metro Cammell (now Alstom) and began service in 1997.[1] Its sister stock is the 1995 Stock used on the Northern line, having been built at a similar time by the same manufacturer.

The stock was used initially in six-car trains, expanded to seven-car trains in 2005. It is fitted with a digital voice announcement system and dot-matrix displays to provide passenger information.

Context

The development programmes of 1995 stock and 1996 were conducted in parallel. Detailed design was done by Alstom S.A. at its Birmingham and Rugby facilities, and the first six train sets were manufactured in Alstom's Barcelona factory to the 1996 stock design. All type approvals were conducted on these early train sets. 1995 stock was produced in the Barcelona factory afterwards, and the balance of the 1996 stock followed. Final assembly and equipping was at Alstom's facility at Washwood Heath, Birmingham, on adjacent production lines.

1995 and 1996 stock are similar but have different interiors, seating layouts and cabs (designed by Warwick Design Consultants), traction packages and train management systems, and slight differences in tripcock geometry. 1995 stock uses LED body-side lights, 1996 stock filament bulbs. The most apparent difference is the bogie: 1996 stock uses an Alstom bogie with a rubber suspension, 1995 stock has AdTranz bogies with air suspension to cope with the arduous track conditions of the underground portions of the Northern line. The main technical differences arose because 1996 stock was designed for "cheapest first cost", while 1995 stock was designed for "life cycle cost", as Alstom had won the contract to act as service provider and maintainer of this stock. Alstom subsequently won the maintenance contract for 1996 stock, to be carried out at the new Stratford market depot in East London.

Delivery and original configuration

The stock was bought for the opening of the Jubilee Line Extension (JLE) from Green Park to Stratford. However, the opening of the JLE was delayed, and the 1996 stock replaced 1983 stock between Christmas Eve 1997 and July 1998, over a year before the JLE opened.

The original plan was to refurbish 1983 stock with the same exterior and interior as 1996 stock, even with double doors, but it proved too expensive. The stock is operated with a dead man's handle at the driver's right hand. When the train is stationary, the top of the handle is turned away from the position in which the driver holds it. To set the train in motion, the driver turns the top of the handle and pushes forward a red lever (This assembley is known as a Traction Brake Controller or TBC). The trains were designed for automatic train operation, as on the Victoria and Central lines, using a Westinghouse system, but operational problems and the cost of upgrading the lineside signalling infrastructure meant that this system did not enter service. A new system called Transmission-Based Train Control (TBTC) has been installed, based on the Alcatel SelTrac used on the Docklands Light Railway; this is the first application of this system on an underground mass transit line. It is a moving block signalling system that will allow trains to run faster and closer together without compromising safety, allowing tube lines to meet more stringent timetable and passenger loading targets.

The original seat covers were a mauve and grey moquette. They formed the letter J for Jubilee (the Northern line's moquette forms the letter N). In November 2005 cars were refurbished, and the seat covers replaced with the new dark blue Tube Lines moquette with multi-coloured and multi-size hollow squares. Newer cars were ordered with this moquette. The Piccadilly line's 1973 stock also has it, and it has been introduced in the Northern line stock. The armrests were purple, but have been repainted blue to match the new seat covers. However, the Mark 2 trains delivered in late 2005 were still carrying the old internal layout in December 2008. All units on the line were completely replaced by the new Barman moquette in 2012 prior to the London 2012 Olympics.

The trains also had signage displayed on the ending side windows with two plus two on each side of the carriages and one plus one close to the driving cabs, the outside mentioning 'Jubilee line' and the inside 'Security cameras in operation'. They were removed during the seventh car project, only train numbers 96066 to 96466 and 96012 to 96412 still retain them.

The stock was delivered as six-car trains, with two three-car units coupled together, each consisting of a Driving Motor car [DM], a Trailer car [T] and an Uncoupling Non-Driving Motor car [UNDM]. The standard train formation was DM–T–UNDM+UNDM–T–DM. Twelve later trailer cars had de-icing equipment; these are referred to as De-Icing Trailer cars [DIT].

The cars are odd-numbered at one end of the train, even numbers at the other. Each number has five digits: the first two are the stock type (96); the third refers to the car type: 0 or 1 for DM, 2 or 3 for T, 4 or 5 for UNDM and 8 or 9 for DIT. Thus, for example, a six-car train set would be 96001, 96201, 96401, 96402, 96202, 96002. Each car is given a letter designation. The even cab car is A, odd cab car B, even UNDM C, odd UNDM D, trailer cars E, DIT F.

Addition of seventh car

In early 2005 London Underground announced that it would add a seventh car to each train and four new trains. The original factory on the Barcelona sea front had been closed, and the new stock was manufactured in Alstom's new factory at Santa Perpètua de Mogoda in the Barcelona suburbs. The four new trains were built as six-car trains and modified to seven-car configuration at Stratford Depot.

From 25 December 2005 the line was closed for completion of the conversion to seven cars, including signalling alterations and software modification to the platform-edge doors. The original plan was to hard-wire two cars together so that the onboard computer would "see" them as one car, but this proved unnecessary. Since the stock was designed as six-car sets with the ability to add a seventh car, platforms were already long enough for seven-car trains and platform-edge doors had been built with space for a seventh car. The line was scheduled to close for five days, but the work was completed ahead of schedule and the line reopened two days early. The new car is a trailer car in the "odd" unit, with design designation "G". An example of a seven-car train set would be 96117, 96317, 96717, 96517, 96518, 96318, 96118 (the seventh car in bold.)

There were various differences between the new and old cars at the time of introduction:

Many of these are likely to change as the old cars undergo refurbishment. The new cars are numbered 96601 to 96725 (odd numbers only). The door sill on the new cars reads "Alstom 1996" for continuity reasons, but they feature the newer Alstom logo instead of the original GEC-Alsthom.

The refurbishment was designed by Warwick Design Consultants, who also designed the moquette. They were also responsible for the Northern and Piccadilly Line refurbishment designs including the driver's cabs and controls.[3]

After the introduction of the seventh car, the passenger information system was upgraded to play next station announcements as stations are approached.

Digital voice announcements

The stock has a digital voice announcement (DVA) system and dot-matrix displays to provide passenger information. The voice announcement system uses two voices: one female voice for station announcements and for alerts such as "please keep your personal belongings with you at all times", another to announce the destination. Announcements are made on trains as they approach a station and on platforms.

Between stops, the announcements scroll across the displays. The original recording is used for "This train terminates at ... station", but the station announcements have been modified since the installation of the DVA system, leading to a disparity between the two halves of some announcements. The occasional use of a male announcer for general passenger alerts and information like station closures makes the Jubilee line the second London Underground line to use a male voice in its DVA system, after the Piccadilly line (which lost its male voice when it was refurbished).

The regular dot matrix pattern at Green Park is:

Green Park - Destination : Stanmore

Traction control

1996 stock interior following refurbishment

1995 and 1996 stocks have similar body shells but they use different AC traction control systems. The 1995 stock system is more modern, since the 1996 stock design specification was frozen in 1991.

1996 stock uses three-phase induction motors fed from a single-source inverter using a GTO (gate-turn-off) thyristor derived from those on Class 465 Networker trains. The 1995 stock uses Alstom's "Onix" three-phase Insulated Gate Bipolar Transistor (IGBT) drive.

Earlier stock, like most electric trains before the 1990s, used DC motors. These are now regarded as inefficient, partly because they are traditionally controlled by resistors, and partly because a 3-phase AC induction motor can provide higher specific power and volumetric power density. The brushes and commutator of a DC motor are prone to wear and require regular maintenance, while an induction machine does not.

In an AC motor supplied by a fixed-frequency supply, however, maximum torque can only be achieved when the resistance of the rotor windings is equal to their reactance. AC motors in an industrial setting are normally operated at approximately constant speed, so if a wound-rotor machine is employed large banks of resistors can be used on start-up to raise resistance and maintain torque. This would be inefficient in a small motor designed for stop-start operation.

Thus it was only the adoption of electronic control systems from the 1980s that made AC traction viable for trains. The motor can be supplied using an inverter, and by varying the inverter's output frequency it is possible to keep the frequency of the current in the rotor windings, and hence the reactance, constant. (The reactance depends on frequency, whereas the resistance is fixed.)

The GTO thyristor achieves this by "chopping" the supply voltage in order to drive a sinusoidal current in the motor windings (pulse width modulation), creating the characteristic whine associated with the stock and with the Class 465 Networker trains that share its traction drive system. The sound changes as the pulse length changes. The noise is produced by the switching frequency current ripple and the resulting torque pulsation experienced by the rotor of the induction machine.

More modern AC traction, such as on 1995 stock, uses an IGBT (which is essentially a combination of the MOSFET and BJT), which can operate at much higher switching frequencies than the GTO. The whining sound is far less noticeable because of the higher switching frequency of IGBT drives.

References

  1. 1 2 3 Mitchell, Bob. Jubilee Line Extension: From Concept to Completion. London: Thomas Telford. pp. 127–134. Retrieved 17 April 2016.
  2. 1 2 3 4 5 6 Neil, Graham. "London Underground Rolling Stock Information Sheet" (PDF). WhatDoTheyKnow. Retrieved 17 April 2016.
  3. ↑ "Transforming the Tube" (PDF). Transport for London. July 2008. Retrieved 28 May 2009.

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