The Anonymous Widower

A Detailed Look At A Three-Car Aventra

In Bombardier and CAF To Make 413 Carriages For New West Midlands Franchise, I wondered if the three-car Aventras ordered by West Midlands Trains had a battery capability.

The Train Weight

I need a good estimate of the weight of a typical Aventra carriage.

Wikipedia gives the following values.

  • Bombardier Aventra – A nine-car Class 345  train weighs less than 350 tonnes, which gives a figure of 39 tonnes per car.
  • Siemens Desiro City – A twelve-car Class 700 train weighs 410 tonnes, which gives a figure of 34 tonnes per car.
  • Bombardier Electrostar – A five-car Class 378 train weighs 159.5 tonnes, which gives a figure of 32 tonnes per car.

Bombardier seem to play their weight figures close to their chest, so I’ll just use a figure of 35 tonnes per car. But it does appear that Aventras, could be heavier than Electrostars.

The Battery Weight

I tend to think in terms of New Routemaster hybrid bus batteries, which have a capacity of 75 kWh.  Surely hybrid bus batteries are fairly common and if you were needing a battery for a new application, it might be where you will start.

The best estimate I can make is that a 75 kWh battery weighs about 600 Kg. I will use this until I find a better figure.

Could the weight of the battery explain the increase in weight between an Electrostar and an Aventra?

Aventras Have A Lot Of Traction Motors

From what I’ve seen on the Internet, it appears that Aventras have a lot of powered bogies.

A Three-Car Aventra

I think that a three-car Aventra would have a formation something like.

  • DMSLW – Driver Motor Standard – Wheelchair and Universal Access Toilet
  • PMS – Pantograph Motor Standard
  • DMS – Driver Motor Standard

Note.

  1. I estimate it would have about 230 Standard Class seats in a traditional layout. or perhaps 150 in a Metro layout.
  2. There would be a couple of wheelchair spaces.
  3. Would a toilet be provided on the train? Crossrail puts them in the stations! Does Birmingham?
  4. Each car would be fully motored.
  5. Could each car have its own battery, so they handled their own regenerative braking efficiently?
  6. All the cars would be connected together by an electrical bus fed from the pantograph car.
  7. West Midlands Trains have said the new trains will be 90 mph units.

The capabilities are not unlike the current Class 323 trains.

The Aventras have advantages over the older trains.

  • They are articulated, which gives more space.
  • They are wider inside due to thin, strong car sides and underfloor heating.
  • Design of lobbies has improved.
  • A mixed traditional/metro interior can be used as in Crossrail’s Class 345 trains.

They could also be designed to a slightly longer length if required. But this might have operational and depot issues.

I expect Bombardier will have used every trick and dodge to get this order.

What Size Of Battery Is Needed To Handle Regenerative Braking?

I’ll do the calculation for one car with perhaps a hundred passengers running at 90 mph or 145 kph.

I’ll assume each passenger weighs 80 Kg with all their baggage, which gives a one-car mass of 43 tonnes.

The amount of energy in that one car is a very surprising figure of just 10 kWh.

How Far Could A Three-Car Aventra Go On Battery Power?

In an article in the October 2017 Edition of Modern Railways, which is entitled Celling England By The Pound, Ian Walmsley says this in relation to trains running on the Uckfield Branch.

A modern EMU needs between 3 and 5 kWh per vehicle mile for this sort of service.

The three-car Aventra will be an efficient train, but it will have features like air-conditioning, so I suspect that a figure of 4 kWh per car-mile will be achievable, if the following is done.

  • Air-conditioning is very intelligent and efficient.
  • The train is very well insulated.
  • All electrical equipment on the train like lights, toilets and doors are efficient.
  • Operation ensures batteries are fully charged before entering battery sections.
  • Pantograph operation will be intelligent to snatch a sneaky charge on a short length of electrification.
  • Regenerative braking energy is stored on the train.

3 kWh per car-mile may even be possible.

Suppose the battery in each car had a capacity of 75 kWh. This would give the following ranges with various energy consumption rates.

  • 3 kWh – 25 miles
  • 4 kWh – 19 miles
  • 5 kWh – 15 miles

It certainly is important to get the train as energy efficient as possible.

Increasing the battery capacity will increase the range proportionally.

This would mean that a very efficient train with a double-size battery could go fifty miles without wires.

Where Practically Could These Trains Run?

There are several possibilities.

Camp Hill Line

The Camp Hill Line is an obvious possibility.

A lot is said about the reopening in Future Plans in the Wikipedia entry for the line.

There has also been speculation in the railway press, that chords will be created to allow trains on the line to run directly into Birmingham Moor Street station.

Moor Street Station

If these trains were to run into Birmingham Moor Street station would the bay platforms at the station be electrified?

This would allow the trains batteries to be charged before returning along the Camp Hill Line.

But it would open up interesting possibilities.

With electrification at stations like Stratford-upon-Avon and Leamington to charge the batteries, could services South of Birmingham be run by three-car Aventras running on batteries?

Both |Stratford-upon-Avon and Leamington Spa are under forty miles by road from Birmingham,

I think it could be possible, but West Midlands Trains are acquiring a lot of diesel trains.

Extending Existing Electric Services

From May 2018, the electric services on the Cross City Line will run between Bromsgrove and Lichfield Trent Valley stations.

Could trains running on batteries extend services?

Conclusion

Three-car Aventras are an interesting possibility.

I think we’ll be seeing a lot of them around the UK.

October 19, 2017 - Posted by | Travel | , ,

1 Comment »

  1. […] discussed such a train in A Detailed Look At A Three-Car Aventra, after West Midlands Trains ordered […]

    Pingback by Could Three-Car Aventras Run Services On The Greenford Branch? « The Anonymous Widower | October 19, 2017 | Reply


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