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London Underground Deep Tube Upgrade

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On 15 June 2018, Transport for London (TfL) confirmed its intention “to award Siemens Mobility Limited a contract of around £1.5 billion to design and build 94 new generation Tube trains that will transform the experience of millions of Piccadilly line customers”. The plan is to build the trains at a new factory in Goole, East Yorkshire, which will employ 700 people.

In general, after such an announcement, there is the mandatory 10-day standstill period during which both parties say nothing. The technical details of the new trains will probably emerge just after this issue of Rail Engineer goes to press. In the meantime, what can we expect to see?

The press release mentioned longer, walk through trains and air conditioning, and the accompanying illustration showed all double doors. These features were outlined in TfL’s 2014 New Tube for London (NTfL) Feasibility Report which showed clearly that an articulated configuration needed to be adopted to enable those facilities.

The report stated: “NTfL has identified that it is possible to provide an inter-car gangway by altering the Tube train design to incorporate an articulated configuration with more, shorter carriages. By positioning the vehicle bogies under the ends of two adjoining cars, the relative vertical and lateral movement of the carriage ends is significantly reduced. This enables a shorter, wide gangway to be fitted without loss of train capacity or a reduction in the number of doors.

“The repositioning of the bogies allows all train doors to be double doors. Double doors allow for rapid access and egress which reduces dwell times. Controlling dwell times becomes a dominant factor for achieving high frequency service levels…”

An articulated layout also delivers a train with fewer bogies for a given train length, providing additional under-floor space for the air conditioning equipment.

It seems highly likely that an articulated layout has been chosen and Rail Engineer’s view is that the Piccadilly line trains will have 10 cars.

What other features might be delivered? There are some items that are shared by all modern tube trains and it is reasonable to assume that the following will be features:

Most axles motored to deliver Victoria line traction and braking performance but with 100km/h top speed which will require motorised articulated bogies;

Electrically powered doors with obstacle detection and sensitive edges;

Modern electronic train control with a monitoring system including data and events streamed to the depot for alerts about equipment with performance deviating from the norm;

Interface for TfL’s chosen automatic train control (ATC) – Alstom, Siemens and Thales are on the shortlist;

Provision to enable conversion to driverless operation in the future.

More speculatively, there might be a means to independently power a train to the next station, possibly using the auxiliary battery, in the event of traction power loss.

But the big news is expected to be the articulated layout, breaking the tradition started over 80 years ago with the first tube trains with all the equipment under the floor – the 1935/1938 tube stock, which is still in use on the Isle of Wight.

Read more: Rail Engineer July 2018 – An interview with Network Rail’s stations director and the Rail Partnership Awards return


Malcolm Dobell BTech CEng FIMechE
Malcolm Dobell BTech CEng FIMechEhttp://therailengineer.com
SPECIALIST AREAS Rolling stock, depots, systems integration, fleet operations. Malcolm Dobell worked for the whole of his 45-year career with London Underground. He entered the Apprentice Training Centre in Acton Works in 1969 as an engineering trainee, taking a thin sandwich course at Brunel University, graduating with an honours degree in 1973. He then worked as part of the team supervising the designs of all the various items of auxiliary equipment for new trains, which gave him experience in a broad range of disciplines. Later, he became project manager for the Jubilee Line’s first fleet of new trains (displaced when the extension came along), and then helped set up the train refurbishment programme of the 90s, before being appointed Professional Head of Rolling stock in 1997. Malcolm retired as Head of Train Systems Engineering in 2014 following a career during which he had a role in the design of all the passenger trains currently in service - even the oldest - and, particularly, bringing the upgraded Victoria line (rolling stock and signalling) into service. He is a non-executive director of CPC Systems, a systems engineering company that helps train operators improve their performance. A former IMechE Railway Division Chairman and a current board member, he also helps to organise and judge the annual Railway Challenge and is the chair of trustees for a multi academy trust in Milton Keynes.


  1. They don’t say the trains will have air conditioning, it’s always referred to as “air cooling” from what I’ve seen so I wouldn’t expect perfectly cooled trains all year just yet.

    Malcolm Dobell’s response. The TfL/Siemens press release clearly says “full air conditioning”


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