The Anonymous Widower

Where’s The Emergency Train Power For Crossrail?

Things that can go wrong in a deep rail line do happen and even in the Channel Tunnel, there have been incidents.

There have been two major fires in the Channel Tunnel in 1996 and 2008 and there have also been various train failures.

I am not being alarmist, but as each Class 345 train can carry 1,500 passengers and twenty-four trains per hour will be going through the line for much of the time, there will be an awful lot of people underground at times.

If you look at the specification of a Class 345 train, it has features surely will help recovery if a train breaks down.

I found this snippet on the Internet which gives the formation of the new Class 345 trains.

When operating as nine-car trains, the Class 345 trains will have two Driving Motor Standard Opens (DMSO), two Pantograph Motor Standard Opens (PMSO), four Motor Standard Opens (MSO) and one Trailer Standard Open (TSO). They will be formed as DMSO+PMSO+MSO+MSO+TSO+MSO+MSO+PMSO+DMSO.

This formation and the train design could have positive implications for safety.

  • It looks to me that the train will be two half-trains. Can they be driven independently, as Class 373 trains in the Channel Tunnel can?
  • Half-trains must get around some train failures. If say the pantograph fails on one half-train, the other half-train can take the train to a suitable place like the next station to evacuate the passengers.
  • The trains will also be walk through, so let’s assume that a passenger’s laptop or mobile catches fire, passengers can be moved to another safe part of the train.

I suspect that all the experience of running electric trains in long tunnels for several decades all over the World, will have been used in validating the design of Class 345 trains.

My biggest worry as an electrical engineer and a Londoner, is a complete electrical failure in the capital.

They don’t happen often, but this article on the BBC is entitled Blackout hits London’s Soho on Black Friday.

It describes London’s power failure of last week.

Power failures do happen, so what happens if a computer virus or extreme weather blacks out London?

I have just read this article in Rail Engineer, which is entitled Crossrail – approaching the final stages.

This is said about the power supply in the tunnels.

The Crossrail route will be powered by a 25kV overhead line system using a Cariboni 110mm deep rigid overhead conductor bar throughout the tunnels. Although from a different manufacturer, this design concept is similar to the one being installed in the Severn Tunnel that doesn’t require weights and pulleys.

In the central section, 25kV traction power for the Crossrail trains will be provided by two new bulk supply points from National Grid 400kV, at Pudding Mill Lane in the east and Kensal Green to the west. Super grid transformers have been installed and fitted with fans and additional coolants.

A 22kV high-voltage network will be installed in the central section from Royal Oak Portal in the west to Limmo Peninsula in the east with an 11kV high-voltage non-traction spur to be installed from Limmo through to Plumstead. This network will supply mains power to each Crossrail station, shaft and portal within the central section.

Note.

  • It is a very simple power layout, for the trains, with a continous overhead rail providing power.
  • There is only two feed points for the overhead power to the trains, but these feed points seem to be of a robust design.
  • Trains in the middle will be fed by power coming a long way in the conductor rail.
  • Conductor rail must be a more robust power supply to the trains, than the typical overhead wires.
  • All Crossrail stations and shafts will use Crossrail’s own dedicated power supply.

The article though doesn’t mention two things.

  • How is an emergency power failure handled?
  • How is the power from regenerative braking fed back into the power network?

I’ll deal with the power failure first.

It would appear that a Central London power failure such as last Friday should have little effect on an independently-powered Crossrail. I wouldn’t expect anything less.

But there are always unexpected reasons, why a train may be isolated without power. So how does a train get to the next station or evacuation shaft, with its valuable load of passengers?

With respect to the regenerative braking, the power is usually fed into the overhead wires and used by another train nearby.

But, I do wonder if Crossrail will be doing things differently, as I like to think of the line as the latest and most energy-efficient of train lines.

Both the braking and failure problems are made easier, if the train is fitted with an on-board energy storage system or batteries in everyday parlance.

A fully-loaded Crossrail train going at its maximum speed of 145 kph will have an energy of  105 KwH, so if it stored this energy on the train when it brakes and stops, it could use it when it accelerated away.

Using batteries for regenerative braking has other effects.

  • It relegates the overhead rail to providing top up power as the train proceeds through the tunnel.
  • The overhead rail and its power supply, only has to cater for energy going to and not coming from the train.
  • The engineering on the train is simpler, as braking energy doesn’t have to be raised to 25 KVAC to feed back into the overhead rail, using perhaps a heavy transformer.

But most importantly, it means that the train has stored energy to proceed to the next station or safe place, if the overhead power should fail.

I have no evidence that this is actually the case, but Bombardier have said that the train will have a remote wake-up facility, so that the driver will turn up and find a train ready for action. Try doing that without a substantial on-board power source, without leaving the train plugged in to electricity all night.

Bombardier are only stealing ideas, from some of the latest cars, if I’m right.

Conclusion

I wouldn’t be surprised if Crossrail’s Class 345 trains are fitted with on board energy storage. The storage would handle.

  • Regenerative Braking
  • Emergency get you to safety power.
  • Remote wake-up of trains.

The design would also mean that the Crossrail and its new trains would be more energy efficient.

 

 

November 30, 2016 - Posted by | Travel | , , ,

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