The final design and some of the engineering challenges for a new fleet of London Underground tube trains have been shown off by the manufacturer.
Externally not much has changed from early concepts, but there’s been a refinement of the interior, and more details announced about how they will operate.
Siemens was awarded the £1.5 billion contract to build 94 new trains in 2018, to replace the ageing, and increasingly expensive to maintain Piccadilly line trains which have been in service since the 1970s.
Half the trains are being built at Siemens existing factory in Vienna, but the other half are to be built in Goole, East Yorkshire, where Siemens is building a new factory and research centre.
There are two sides to any new train project, the passenger and the operator.
The passenger wants a bigger more comfortable train, and the operator wants one that’s cheaper and easier to maintain.
For passengers, the new train will be fully walkthrough from end to end, will come with the world’s first deep-level tunnel air conditioning system, and live in-tunnel information screens about transport services. The outside of the trains will also include digital displays with the destination on them. The new trains should also offer a smoother ride.
Wider doors are more accessible, but also means people can get on and off quicker so that, on average, trains spend less time in the station. Less time stopped at stations means slightly faster journeys.
For comparison, the current trains have double doors of 137cm wide and single doors at the carriage ends that are 68cm wide. The new train’s doors will all be 169cm wide.
With a larger footprint inside, they will be able to carry 10% more people, and with the shorter dwell time in stations, the Piccadilly line will be able to fit an extra three trains per hour in the rush hour, giving the Piccadilly line nearly a quarter more capacity from 2027.
There is also a — currently on hold — plan to upgrade the signalling system on the Piccadilly line, which would increase capacity from 27 to 36 trains per hour
The first trains are due to arrive in passenger service in 2025.
From the operator’s perspective, a lot of work between TfL’s engineers and Siemens has resulted in some interesting innovations.
One of the heaviest parts of any train are the bogies underneath the carriage which houses the wheels, brakes and motors. The new trains, because they’re multi-articulated to support walkthrough carriages can also use fewer bogies underneath. Reducing the weight reduces how much energy is needed to move the train – by some 20% overall. It also reduces wear and tear on the tracks themselves, so less maintenance is needed.
That means fewer weekend closures of the Piccadilly line.
The new trains will also include regenerative braking, a method of returning energy normally lost as heat in the tunnels back into electricity, so less heat and lower running costs. They also include a new traction system using low-loss permanent magnet motors and auxiliary electric systems.
The trains are also expected to be easier to maintain than current designs, and with sensors throughout the train’s equipment, they should be able to predict when components are likely to fail, and proactively maintain them to reduce train failures when in service.
TfL is having to work on upgrading its maintenance depot at Northfields to support the new trains, and that work is underway at the moment.
The new trains also have the theoretical ability to be upgraded at a later date to driverless operation, but that would at a minimum require a huge amount of upgrades to the stations first.
But in the short term, the Goole factory contracts are being awarded, the first assembly staff being trained, and the first trains should be delivered in 2024 for testing by TfL.
Passengers can expect to try them out from 2025.