The Anonymous Widower

Is A Bi-Mode Aventra A Silly Idea?

In How Long Will It Take Bombardier To Fulfil Their Aventra Orders?, when discussing the new West Midlands Trains franchise, that has recently been awarded, I said this about the proposed eighty new carriages for the Snow Hill Lines.

As it is unlikely that the Snow Hill Lines will be electrified in the near future, could we be seeing an Aventra bi-mode for the Snow Hill Lines?

So is the bi-mode Aventra a silly idea?

The Five-Car Aventra

It looks like the formation of a five car Aventra like a Class 720 train is something like DMSLW+MS+MS1+PMS+DMSL

The codes are as follows.

  • D – Driving
  • L – Lavatory
  • M – Motor
  • S – Standard Class
  • W – Wheelchair

So this means the following.

  • All cars are motored for fast acceleration and smooth regenerative braking.
  • As all cars are motored, there must be a heavy-duty electrical power bus running the length of the train.
  • Both driving cars have a toilet.
  • The wheelchair area and the fully-accessible toilet are probably together in one driving car.
  • The pantograph is on one of the middle three cars.

It should also be noted that the Aventra has a slightly unusual and innovative electrical layout.

This article in Global Rail News from 2011, which is entitled Bombardier’s AVENTRA – A new era in train performance, gives some details of the Aventra’s electrical systems. This is said.

AVENTRA can run on both 25kV AC and 750V DC power – the high-efficiency transformers being another area where a heavier component was chosen because, in the long term, it’s cheaper to run. Pairs of cars will run off a common power bus with a converter on one car powering both. The other car can be fitted with power storage devices such as super-capacitors or Lithium-ion batteries if required.

This was published six years ago, so I suspect Bombardier have refined the concept

It would appear that this could be the reason, why in the document I found MS1 was used for one of the intermediate cars, as this is the car with space for the energy storage.

Do Aventras Have Batteries For Regenerative Braking?

Until I get a definitive statement from Bombardier, that they don’t, I will believe that they do for the following reasons.

But the main reason, is that as an Electrical Engineer, I believe it to be stupid and seriously bad design to not use some form of energy storage to handle the energy produced by regenerative braking.

Energy Storage In A Bi-Mode Train

If you look at the five-car Class 720 train, all axles are motored. This will give fast acceleration and smooth regenerative braking, which is just what both train operators and passengers want.

If a bi-mode train had energy storage, if say its speed was checked by a yellow signal, it would be able to regain line speed using the energy stored when it slowed down. So passengers wouldn’t have to endure the vibration of the diesel engine and the jerks as it started.

No competent engineer would ever design a modern bi-mode train without energy storage.

Where Would You Put The Power Pack On An Aventra?

Although space has been left in one of the pair of power cars for energy storage, as was stated in the Global Rail News article, I will assume it is probably not large enough for both energy storage and a power pack.

So perhaps one solution would be to fit a well-designed power pack in the third of the middle cars, which would then be connected to the power bus to drive the train and charge the battery.

This is all rather similar to the Porterbrook-inspired and Derby-designed Class 769 train, where redundant Class 319 trains are being converted to bi-modes.

Diesel Or Hydrogen Power Pack

Diesel will certainly work well, but London and other cities have hydrogen-powered buses.

The picture is from 2013, so the technology has probably moved on. This Fuel Cell Bus section in Wikipedia gives the up-to-date picture.

Automatic Power Source Selection

Effectively, the ideal bi-mode train will be a tri-mode and will have the following power sources.

  • Traditional electrification.
  • On board diesel or hydrogen power.
  • Energy storage, charged from the electrification or from regenerative braking.

The power source would be chosen automatically to minimise the use of both diesel/hydrogen power and electric power from the electrification.

Modern trains like an Aventra can raise and lower the pantograph automatically, so they can do this to make best use of what electrification exists to both power the train and charge the energy storage.

Techniques like these will be used to minimise the use of the diesel or hydrogen power pack.

Intermittent And Selective Electrification

On lines like the Snow Hill Lines sections could be electrified, where the engineering is easy and affordable, to with time reduce the use of unfriendly diesel or expensive hydrogen.

Strangely, one of the first places to electrify, might be the tunnels, as after the electrification of the Severn Tunnel, our engineers can probably electrify any railway tunnel.

I also don’t see why third rail electrification can’t be used in places like on top of viaducts and in well-designed station installations.

The 125 mph Bi-Mode Aventra

This article on Christian Wolmar’s web site is entitled Bombardier’s Survival Was The Right Kind Of Politics. This is said.

Bombardier is not resting on its laurels. Interestingly, the company has been watching the problems over electrification and the fact that more of Hitachi’s new trains will now be bi-mode because the wires have not been put up in time. McKeon has a team looking at whether Bombardier will go into the bi-mode market: ‘The Hitachi bi-mode trains can only go 110 mph when using diesel. Based on Aventra designs, we could build one that went 125 mph. This would help Network Rail as it would not have to electrify everywhere.’ He cites East Midlands, CrossCountry and Wales as potential users of this technology.

So Bombardier don’t think it is silly. Especially, the statement that Bombardier could build an Aventra that could do 125 mph running on diesel.

Applying, what we know about the power in the bi-mode Class 800 and Class 769 trains, which have three and two diesel power-packs respectively, I suspect that to create a five-car Aventra, that is capable of 125 mph on diesel, would need the following.

  • At least three diesel power-packs.
  • Regenerative braking using onboard energy storage.
  • Automatic pantograph deployment.
  • Automatic power source selection.

The light weight of the Aventra would be a big help.

It is my belief that energy storage is key, for the following reasons.

  • Stored energy from braking at a station from 125 mph, would be used to get the train back to operating speed, without using a large amount of diesel power.
  • Braking and acceleration back to operating speed, perhaps after being slowed by another train, might not need the diesel engines to be started.
  • Starting a journey with an optimum amount of power in the battery might make getting to operating speed easier.

It would be a rough engineering challenge, but one I believe is possible.

Consider the routes mentioned.

East Midlands

Consider.

  • 125 mph running would certainly be needed on this route.
  • Battery power could be used to boost the trains to 125 mph.
  • Electrification will be available between St. Pancras and Kettering.
  • Electrification might be impossible between Derby and Sheffield because the Derwent Valley is a World Heritage Site.

Some form of charging might be needed at Derby, Nottingham and Sheffield.

A bi-mode train would be ideal for Norwich to Liverpool, although there’s not a great deal of electrification.

Cross Country

CrossCountry use several electrified lines on their various routes..

  • York to Edinburgh
  • Birmingham New Street to Manchester Piccadilly
  • Bournemouth to Basingstoke
  • Stansted Airport to Ely

Note that parts of some of these routes allow125 mph and Bournemouth to asingstoke is electrified using third-rail.

A dual voltage, 125 mph bi-mode train would probably fit CrossCountry’s routes well.

Wales

Except for the South Wales Main Line, there’s little electrification in Wales, but a 125 mph bi-mode train could be used on the following several partially-electrified routes.

  • Carmarthen to Manchester Piccadilly.
  • Holyhead to Manchester Piccadilly
  • Holyhead to Liverpool via the Halton Curve.
  • Birmingham to Shrewsbury.
  • Swansea to Newport

Currently most of these services are served by 100 mph  Class 175 trains.  If nothing else, they would probably be more spacious, faster and fuel-efficient.

Conclusion

A five-car Aventra bi-mode is definitely not a silly idea.

It would be a sophisticated train with the following characteristics.

  • Electric drive
  • Regenerative braking.
  • 25 KVAC overhead and 750 VDC third rail capability.
  • Automatic pantograph deployment.
  • Onboard energy storage.
  • Automatic power source selection.
  • Diesel or hydrogen power-pack
  • 125 mph capability.

The first four are probably already in service in the Class 345 train.

.

August 21, 2017 - Posted by | Travel | , , , , , ,

4 Comments »

  1. […] I discuss the concept of a bi-mode Aventra in Is A Bi-Mode Aventra A Silly Idea?. […]

    Pingback by How Long Will It Take Bombardier To Fulfil Their Aventra Orders? « The Anonymous Widower | August 22, 2017 | Reply

  2. […] In Is A Bi-Mode Aventra A Silly Idea?, I outlined what I believe the ultimate bi-mode train will be like. […]

    Pingback by Electrification ‘Very Unlikely’ To Come Back Into EWR Scheme « The Anonymous Widower | August 26, 2017 | Reply

  3. […] in Is A Bi-Mode Aventra A Silly Idea?, I link to an article on Christian Wolmar’s web site, which says that Bombardier are looking […]

    Pingback by The Intelligent Multi-Mode Train And Affordable Electrification « The Anonymous Widower | October 7, 2017 | Reply

  4. […] In Is A Bi-Mode Aventra A Silly Idea?, I looked at putting a diesel power-pack in  a Class 720 train, which are Aventras, that have been ordered by Greater Anglia. I said this. […]

    Pingback by Could Bombardier Build A Hydrogen-Powered Aventra? « The Anonymous Widower | October 29, 2017 | Reply


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s