The Anonymous Widower

The Formation Of A Class 710 Train

This morning, I was able to look at the plates on all four cars of a Class 710 train.

Here is the formation of the train.


The plates on the individual cars are as follows.

DMS – Driving Motored Standard

  • Weight – 43.5 tonnes
  • Length – 21.45 metres
  • Width 2.78 metres
  • Seats – 43

The two DMS cars would appear to be identical.

PMS (W) -Pantograph Motored Standard

  • Weight – 38.5 tonnes
  • Length – 19.99 metres
  • Width 2.78 metres
  • Seats – 51

The (W) signifies a wheelchair space.

MS1 – Motored Standard

  • Weight – 32.3 tonnes
  • Length – 19.99 metres
  • Width 2.78 metres
  • Seats – 52

It is similar in size to the PMS car, but has an extra seat.

These figures add up to the unit figures you would expect.

  • Weight – 157.8 tonnes
  • Length – 82.88 metres
  • Seats – 189

But what else can be said?

All Cars Are Motored

All four cars are motored, which is not an arrangement seen very often in UK electrical multiple units.

  • Most British Rail units like Class 317, 319 and 321 trains have only one motored car.
  • Five-car Class 800 trains have two trailer cars and nine-car trains have four trailer cars.
  • Eight-car Class 700 trains have four trailer cars and twelve-car trains have six trailer cars.

Class 345 trains which are also Aventras, have eight motored cars and only one trailer car.

I suspect that it is an arrangement that gives advantages, over the weight and cost of the extra motors.

Less Force Between Wheel And Rail

The tractive and braking force between the wheels and the rail will be less to get the same acceleration and deceleration, as the force will be divided between all traction motors and wheels.

Does applying the power at all wheels mean that the train accelerates and decelerates faster, thus cutting station dwell times?

Does this mean that wheel slip, which damages wheels and rails is less likely?

Are the lower power traction motors more reliable?

Can A Motored Car Be Changed Automatically To A Trailer Car?

Suppose a traction motor or its controlling system packs up, can the train’s central computer switch it out and effectively convert the errant motored car into a trailer car.

On a 710 train, that would mean a 25 % loss of power, but surely the train has sufficient power to be driven to the next station?

Equalisation Of Forces Between Cars

The forces between the four cars must be equal and possibly low at all times, as you have four identical individually-powered, computer-controlled vehicles moving in unison.

Does this give passengers a smoother ride?

Does it mean that walking between cars is an easier process?

I think so and I can only think of the problems of getting a four-person pantomine caterpillar working properly!

A Logical Way To Power A Train

Could it be that this is the logical way to power a train, but you need precise computer control of all cars to take full advantage?

It strikes me that getting it right could be a very difficult piece of computing, so has this been causing the delays for the Class 710 trains?

I don’t think we’ll know the answers to all my questions, until Bombardier publish a full authorised philosophy.

Twenty Metre Long Cars

British Rail designed a lot of trains to be eighty metres long give or take a metre. So there are a lot of platforms in the UK, that can accommodate an eighty-metre long train.

All of the London Overground routes, where these trains will run have platforms that can accommodate 80, 100 or 160 metre long trains.

So they could be run by a single train or two trains running together as appropriate without any expensive platform lengthening.

The Two Driving Cars Appear Identical

This must be logical.

Many older electrical multiple units have different driving cars.

Sod’s law states that one type will be less reliable than the other, so you’ll end up with a shortage of trains.

But if both driving cars are identical, you have much less of a problem.

What Will Be The Formation Of a Five-Car Class 710 Train?

If all cars are to be powered then it will be.


MS2 and MS1 would be identical.

Would you really want to add a new trailer car into the fleet to complicate maintenance?

Why Are The Trains For The Lea Valley Lines Not Eight-Car Trains?

On the Lea Valley Lines, London Overground have said that they’ll generally run two four-car trains as an eight-car train.

In Latest On The New London Overground Class 710 Trains, I discussed the possibility of changing the order to a number of eight-car trains and felt there could be advantages.

  • Higher passenger capacity in the same train length.
  • An eight-car train would contain only two DMS cars instead of four.
  • Trains could be built as two four-car half-trains, to improve reliability.
  • Passengers would be able to walk the full length of the train.

Bombardier and London Overground must have analysed this and as they have more information than I do, they have come to a different conclusion.

Is there for instance, a safe procedure, that uses the operational train to transfer passengers to a safe place and then drag the failed train to appropriate parking?

  • With an eight-car train, you’d have no operational train to take passengers to safety.
  • With two four-car half-trains, as in Crossrail’s Class 345 trains, would you have other problems? But the Croosrail  trains are designed for a long tunnel, with difficult evacuation problems.

There must be a very valid reason.


The Class 710 train has been well-designed and is not your normal suburban train.



May 27, 2019 - Posted by | Transport/Travel | ,


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