Cheaper railway electrification

Post by **adam2** » 21 Oct 2007, 16:19

Electric railways have many advantages including no pollution at the point of use, and the ability to use electricity from any source, including renewables.
The principle drawbacks are the very substantial capital costs, and the vulnerability to any interuption in the power supply.

I believe that these disadvantages may be overcome by using a new design of electric locomotive or electric multiple units. These should incorporate a battery with sufficient capacity to move the train at reduced speed for perhaps ten miles.

The use of such trains should result in very dramatic savings on the cost of infrastructure.
The vast cost of railway electrification is not primarily due to the cost of overhead wires, supports, transformers etc. The real money is spent on lowering the track in tunnels, raising the height of bridges, and altering staions, in order to provide the required clearances between the 25,000 volt wires and anything else.
Many bridges, tunnels and other structures are listed, which adds even more expense.

Use of battery assisted trains would avoid the need for any of this expensive and very disruptive work. Wherever clearences are insufficient, the over head wiring would be terminated each side of the limited clearence section, and the train would proceed on battery power.
(in order to reduce wear on the battery, drivers would be instructed to coast through dead sections whenever possible.)
In the event of a power failure, a battery assisted train should be able to continue to the next station, from whence passengers may be conveyed by other means, clearly better than being stuck miles from anywhere, or in a tunnel.

If the train can not proceed due to an accident or breakdown ahead, then the battery could supply internal lighting and ventilation for many hours.

The train could also be moved at low speed on battery power in the depot for cleaning, filling of water tanks etc. This would improve safety and simplify/cheapen the equiping of the depot.

There could also be energy savings by using regenerative braking to charge the battery, this would avoid the hazards of trying to return surplus power to the overhead line.

Battery power has been considered in the past and has been rejected due to the cost, weight and bulk of the battery. Recent advances in batteries (largely driven by the development of hybrid road vehicles) should make the idea more practical than in the past.

Note that the above is not my own work, I qoute it , with permision from a railway engineer whom I met recently. I do however agree that the idea is worth pursuing.

stumuz · Post by **stumuz** » 21 Oct 2007, 18:48

This does indeed sound like a good idea. However, does it suffer from the same lacuna that every householder faces when the time comes to install a wind/PV generating capacity? If I assume that the grid will still be working in 20 years time then grid wins absolutely. If I assume that PO will lead to grid crash then battery will be king.

MacG · Post by **MacG** » 21 Oct 2007, 20:38

Did the original inventor consider the current state of things with reference to lead, nickel and copper?

Bandidoz · Post by **Bandidoz** » 22 Oct 2007, 05:23

This sounds like a means of moving the cost from the infrastructure to the rolling stock, and I doubt that would be a wise move.

I guess it *could* be possible to avoid electrification inside tunnels that are inclined downhill. Otherwise there could be a problem if the train was running on offline power then got itself into a zone where it couldn't recharge. But then what if the "uphill" tunnel going the other way got closed temporarily and had to cover both scenarios?

Nah, it's a non-starter.

The number one priority for resilience on the railway would of course be the signalling system. Temporary stoppage of rolling stock is a mere inconvenience, but it is failsafe. Temporary stoppage of the signalling and points system, with rolling stock on "battery-backup"......

PS_RalphW · Post by **PS_RalphW** » 22 Oct 2007, 10:07

Not sure about signalling, although I seem to think the victorians managed without electricity, but why not use a 'plug in' diesel electric
hybrid locomotive? Diesel electric has been arround since the 1960s
(if not earlier). They can certainly provide the backup power. I can
see the constant switching of power supplies as being a technically difficult, but not impossible.

I would love to buy a lightweight electric car big enough for four adults,
50 mile electric range with a small diesel generator for the rare long journeys. No one has built one yet...

Post by **adam2** » 25 Oct 2007, 14:53

MacG wrote:Did the original inventor consider the current state of things with reference to lead, nickel and copper?

I dont think that it was considered, though it must be said that those materials are still readily available, though at increasing prices.

Post by **adam2** » 25 Oct 2007, 14:58

Bandidoz wrote: The number one priority for resilience on the railway would of course be the signalling system. Temporary stoppage of rolling stock is a mere inconvenience, but it is failsafe. Temporary stoppage of the signalling and points system, with rolling stock on "battery-backup"......

I dont believe that the proposal would lead to safety problems in event of the power to signalling equipment failing.

Signals are designed to automaticly give the stop or danger indication in case of power failure. After all, diesel trains still run, and electric ones can coast for miles, I have never heard that this is a safety problem.

Bandidoz · Post by **Bandidoz** » 25 Oct 2007, 17:30

What I meant by that is that the power-fail-resilience needs to be in the signalling system before rolling stock are considered. Moot point, really.