The Anonymous Widower

Thoughts On The New Tube For London

This article on the BBC is entitled East Yorkshire Factory Wins £1.5bn Tube Train Deal.

This is the second paragraph.

Transport for London (TfL) said the 94 trains will be designed and built by Siemens Mobility at its planned £200m facility in Goole.

But what else do we know of the design?

In 2013, I went to an exhibition of Siemens’ early design study, which I wrote about in Siemens’ View Of The Future Of The Underground.

These are the pictures I took at the time of the mock-up in the exhibition.

From my visit, I ascertained the following.

  • The cross section appears taller and wider than the current deep-level trains.
  • It has been designed so that someone of 2.6 metres can stand without stooping.
  • The trains are designed to be articulated with a walk-through gangway.
  • Access appears to be level between train and platform.

Will the new trains be like the mock-up?

This article on Rail Engineer is entitled London Underground Deep Tube Upgrade.

It gives some useful information and clues about the design of the New Tube for London (NTfL).

  • The press release mentioned longer, walk through trains and air conditioning.
  • An illustration with the press released shows all double doors.
  • It is possible to provide an inter-car gangway by using an articulated configuration with more, shorter carriages.
  • Bogies appear to be shared between cars.
  • Bogie positioning allows all doors to be double.
  • Rail Engineer’s view is that there are ten cars to a train.
  • Most axles motored to deliver Victoria Line traction and braking performance.
  • A 100 kph speed is quoted, as, opposed to 80 kph for current 2009 Stock on the Victoria Line.
  • There might be a battery to power the train in case of power failure.

Taking all of these clues, what can I deduce?

Safe Platform Area

Before continuing, I will define what I mean as the safe platform area.

Usually on most Underground platforms without platform-edge doors, there are barriers at both ends of the platform beyond, which passengers are not allowed.

These limit the end of what I define as the safe platform area, where passengers can freely circulate and enter and leave the trains.

These pictures show the ends of various Underground platforms.

Each picture is identified with Station, Line, Direction and Train End.They all seem fairly similar.

Train Length And Car Length

The press release says the new trains will be longer.

The current length of the 1973 Stock on the Piccadilly Line is 106.8 metres.

This length is determined by the underground platforms, where if the driver stops, so that they can get off into the protected area, at the forward end of the platform, the rear end of the train is still in the tunnel.

The end passenger doors are of course in the safe area of the platform.

From looking at trains at Kings Cross station and judging it against the known length of a 1973 Stock train, I estimate that the length of the safe area is around ninety-five metres.

Looking at the picture of the cab in the mock-up, there is no driver’s door. So I will assume that drivers will access the cab from the passenger compartment. This probably means that the trains could be a little bit longer and still give access to all cars on the train.

The Rail Engineer article speculates that the trains will have ten sections of which two must have cabs on one end.

I think this will mean the following.

  • There will be nine bogies between cars.
  • There will be an end bogies under the cab of both driving cars.
  • Each passenger car and the passenger section of the driving cars, will have two double doors on either side.
  • I believe that the interiors of the passenger cars and the passenger sections of the driving cars will be virtually identical.
  • The driving cab would be perhaps four metres long and could have a plant room behind it.
  • The driving cab and its structure would probably incorporate a crush zone.

If the end pair of doors behind the driver’s cab, were locked out on underground platforms, this would not cause inconvenience to passengers. It certainly doesn’t now, when selective door opening is used at various stations on the Underground, like Baker Street station on the Sub-Surface Lines.

So perhaps, the safe platform area will go to the middle of the passenger compartment in the driving cars?

This will mean that.

  • At some stations only one door can be used in the end cars.
  • Access will always be available through the second door of the car or the two doors in the next car.
  • The driver can easily access the cab, through the bulkhead door between the cab and passenger compartment.

This will also mean that there will be eight passenger cars and two half passenger sections from the driving cars in the safe platform area.

It should be noted that on the Victoria Line trains have always stopped automatically in the correct position, so this wouldn’t be difficult to arrange with automation of this function on the NTfL

Suppose the safe platform area can be stretched to 108 metres, this would mean.

  • The passenger cars would be 12 metres long
  • The passenger sections of the driving car would be 12 metres long.
  • The driving cars would be perhaps 16 metres long.

This would give a total train length of 128 metres, with a passenger compartment that is 120 metres long.

Obviously, these lengths are speculative and others will work.

  • 12.5 metre passenger cars would result in a 133 metre long train and would need a 112.5 metre safe platform area.
  • 13 metre passenger cars would result in a 138 metre long train and would need a 117 metre safe platform area.
  • 14 metre passenger cars would result in a 148 metre long train and would need a 126 metre safe platform area.

I do think the figures show, that if trains can overhang the safe platform area, then trains can be longer and train capacity can be increased.

It also shows, that if the safe platform area can be lengthened, so can the trains, which would further increase capacity.

But lengthening platforms, especially in tunnels can be very expensive!

Train Length On Other Lines

These trains must also fit the Bakerloo, Central, Jubilee, Northern and Waterloo & City Lines.

These lines all have different length trains.

  • Bakerloo – 114 metres
  • Central – 133 metres
  • Jubilee – 126 metres
  • Northern – 108 metres
  • Waterloo & City – 66.5 metres

To further complicate matters, some stations on the Jubilee Line have platform-edge doors.

The Rail Engineer article states that the NTfLwill have ten articulated segments.

If all the passenger cars are identical, then a longer or shorter train should be able to be created by fitting an appropriate number of passenger cars between the two driving cars.

Train Length On The Waterloo & City Line

A five-car train with twelve metre segments and sixteen metre driving cars, would be 68 metres long and could fit the simple platforms of the Waterloo & City Line.

Train Capacity

The capacity of the 1973 Stock is 228 seated and 684 standing passengers.

The most modern deep tube trains on the Underground are the 2009 Stock of the Victoria Line.

These trains accommodate 252 seating and 1196 standing passengers in a train length of 133.3 metres, which is 10.85 passengers per metre.

A better comparison might be the S7 Stock of the Circle Line, as they have similar a seating arrangement to the NTfL.

These trains accommodate 865 sitting and standing passengers in a length of 117.5 metres, which is 7.36 passengers per metre

As the passenger section of the proposed design for the NTfL is 120 metres,

  • This gives a capacity .of 1302 passengers using the 2009 Stock figure.
  • This gives a capacity .of 883 passengers using the S7 Stock figure.

The actual figure is probably somewhere in the middle. I shall use 1100, which is an increase of twenty percent over the current trains.

Train Weight

Obviously, I don’t have the weight of the proposed NTfL.

A 2009 Stock train weighs 197.3 tonnes and is 133.3 metres long.

My guess for the length of a proposed NTfL is 128 metres.

The best I can come up with is to say that the NTfL is the same weight per metre as the 2009 Stock.

This gives the weight of the NTfL as 189.5 tonnes.

I would put an error of 25 tonnes on that figure either way.

Train Kinetic Energy

The value of the kinetic energy of the train is important, as it determines the energy that must be.

  • Transferred to the train to accelerate it up to speed.
  • Absorbed by the braking system, when the train stops.

Consider.

  • The basic train weight is 189.5 tonnes.
  • There are 1100 passengers.
  • With bags, buggies and other things passengers bring on, let’s assume an average passenger weight of 90 kg, this gives an extra 99 tonnes.
  • This gives a total train weight of 288.5 tonnes

If the train is travelling at 100 kph, this gives a kinetic energy of 30.9 kWh.

Regenerative Braking

The S Stock trains of the sub-surface lines have regenerative braking.

This saves energy and it will certainly be applied on the proposed NTfL.

The regenerative energy system on the S Stock returns the electricity through the electrification to power other trains nearby. This means a braking train effectively powers one that is accelerating.

The Rail Engineer article about the NTfL, says that most axles will be powered.

  • This gives good acceleration and smooth regenerative braking.
  • I would not be surprised to see a small battery of about 5 to 10 kWh in each car to handle the regenerative braking.
  • When the train brakes the traction motors will pass their generated energy to the battery.
  • On acceleration, the traction motors would use the energy stored in the battery.

One of the great advantages of using batteries with regenerative braking in tunnels, is that it reduces the amount of heat that a train emits into the trunnel.

Electrical System

I wouldn’t be surprised to see each car designed like a serial hybrid bus.

  • The third-rail electrification and energy from regenerative braking would charge the battery.
  • Each car might have its own pickup shoes.
  • The battery would power the car’s traction motors and other systems.

An intelligent computer system would control each car and the whole train.

Effectively, the train could be a connected string of ten independently powered cars.

Think liberty horses with a ringmaster in charge.

Keeping The Tube Cool

This article on IanVisits is entitled Cooling The Tube – Engineering Heat Out Of The Underground.

Read it and you’ll find all the methods Transport for London are employing to make Underground travel better.

The first thing that must be done is to make sure that the proposed NTfL do not increase the heat input into the tunnels and trains to make the experience hotter

The train must be well-insulated, so that if the temperature in the train is at the required level for passengers, it tends to stay there and only change slowly.

The second thing that must be done is that the train should be designed so that it puts a minimum level of heat into the tunnels.

  • Regenerative braking to batteries will help, as it will mean that braking should be heat-free and the train will be taking less traction current from the rails.
  • An aerodynamic train will produce less heat from friction.
  • Traction motors and other electrical systems will produce heat.

I suspect Siemens will look at every component of the train and heat production will be one of the criteria.

I also believe that the design of an intelligent air-conditioning system is important.

Suppose you are trying to use air-conditioning to cool a 30 °C train in a 30 °C tunnel. All you’ll do is heat the tunnel even more.

Take the Piccadilly, Jubilee and Central Lines, which all have surface sections at both ends.

So why not cool the trains on the surface to say 22 °C, before they enter the central tunnels?

  • There will be no problem venting the heat to air.
  • The outside air temperature on the surface, will probably be less than in the tunnels
  • If the trains are well-insulated, this will help.

By the time the trains get to the other end of the tunnel, the train’s temperature will have risen and then the cycle is ready to start again.

Some trains spend thirty minutes or more running on the surface in a round trip of more than an hour.

Emergency Train Recovery Using Battery Power

If there is sufficient battery capacity, then this must be possible.

Conclusion

These trains could be very different than the trains they replace.

 

July 4, 2018 - Posted by | Travel | , ,

3 Comments »

  1. […] I wrote about this in Thoughts On The New Tube For London. […]

    Pingback by The Battery Trains Are Coming « The Anonymous Widower | July 17, 2018 | Reply

  2. “This would give a total train length of 128 metres, with a passenger compartment that is 120 metres long.”

    In several statements has been anounced that the NTfL (for the Piccadilly line) will be 6 m longer than the current trains, thus:
    106.8+6= 112.8-> thus the passenger cars would come to about 10.5m, and the driving car 14.4m .

    Comment by Danny Alti | August 13, 2018 | Reply

    • I was speculating before the length was disclosed. I like to try and solve mathematical puzzles.

      Comment by AnonW | August 13, 2018 | Reply


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