GWML Electification

[Zomboid]

Electric trains are pretty much always faster accelerating than a diesel. A long time ago my commute involved a train where a 159 would pull away at the same time as an old mk1 based EMU, and the 12_EP unit would be faster right up until it had to slow for the next station.

And those mk1 units weren't exactly super powered, this was on DC where there is less power available in general then an AC system.

 

Faster acceleration is one of the major benefits of electrification.

Edited June 16, 2017 by Zomboid

[Coryton]

Electric trains are pretty much always faster accelerating than a diesel. A long time ago my commute involved a train where a 159 would pull away at the same time as an old mk1 based EMU, and the 12_EP unit would be faster right up until it had to slow for the next station.

And those mk1 units weren't exactly super powered, this was on DC where there is less power available in general then an AC system.

 

Faster acceleration is one of the major benefits of electrification.

 

That certainly was the case but I'm not sure how true that is for more modern trains than the 159 you refer to.

 

It's very noticeable how quickly a 220 accelerates out of a station, for example.

[Zomboid]

A voyager is ridiculously overpowered though. A 4 car 220 has 3000 installed hp, I believe. It was always possible to put a deltic on a 4 coach train and then give the passengers whiplash when accelerating...

 

I suspect the fuel costs if they used that to routinely achieve electric levels of performance would be considerable.

[Zero Gravitas]

I'm guessing it's this one http://www.hondawanderer.com/800101_South_Marston_2017.htm which has been about.

Was London-bound through Didcot at about 12:30 on Monday.

[jonny777]

A voyager is ridiculously overpowered though. A 4 car 220 has 3000 installed hp, I believe. It was always possible to put a deltic on a 4 coach train and then give the passengers whiplash when accelerating...

 

I suspect the fuel costs if they used that to routinely achieve electric levels of performance would be considerable.

 

Yes and 180s have 3750hp for a 5-car unit which is also a ridiculous amount of power. However, they can produce spectacular results. I have been on one which for some reason came down to a crawl in the middle of the Severn Tunnel, and then accelerated up the incline towards Pilning. From walking pace, by the time we exited the tunnel I swear we were doing something in the region of 100mph; it was certainly faster than anything I had experienced before up the 1 in 100.

[Coryton]

Yes and 180s have 3750hp for a 5-car unit which is also a ridiculous amount of power. However, they can produce spectacular results. I have been on one which for some reason came down to a crawl in the middle of the Severn Tunnel, and then accelerated up the incline towards Pilning. From walking pace, by the time we exited the tunnel I swear we were doing something in the region of 100mph; it was certainly faster than anything I had experienced before up the 1 in 100.

 

Ridiculous in what sense?

 

If you assume power should be based on maintaining maximum speed and you get whatever acceleration that gives you (which I believe is how the HSTs were designed) they maybe.

 

But what is wrong with providing sufficient power for rapid acceleration, resulting in faster journeys overall and more capacity?

 

We certainly don't spec car engines so that they can just keep up 70 mph uphill.

 

Surely the 1st generation DMUs that could barely make it up Lickey were the ridiculous ones, power-wise?

[Titan]

Ridiculous in what sense?

 

If you assume power should be based on maintaining maximum speed and you get whatever acceleration that gives you (which I believe is how the HSTs were designed) they maybe.

 

But what is wrong with providing sufficient power for rapid acceleration, resulting in faster journeys overall and more capacity?

 

We certainly don't spec car engines so that they can just keep up 70 mph uphill.

 

Surely the 1st generation DMUs that could barely make it up Lickey were the ridiculous ones, power-wise?

 

Ridiculous fuel consumption. The voyagers are known to be very thirsty. Also much higher maintenance costs. Over specifying  has a big impact on the bottom line, money which the railway industry can't afford to waste. The best designs are those which do exactly whats needed, no more, no less.

[D854_Tiger]

 

 

Surely the 1st generation DMUs that could barely make it up Lickey were the ridiculous ones, power-wise?

 

 

You could lose the will to live on one of those on an all stations stopper from Worcester to Birmingham Snow Hill, especially when going up Old Hill bank.

 

However when they were first introduced, I believe they seemed like Concorde compared to what they were replacing.

 

It's just that in a very few short number of years, when Ford were demonstrating the best that automotive technology could do, it w\as then that the trains were found wanting.

[jonny777]

Ridiculous in what sense?

 

Power to weight ratio.

 

Unless these units are used on stopping services, or were built for a railway where delays are commonplace, the acceleration benefits will only be seen on a small percentage of the journey.

 

If an HST with 10 vehicles (2+8) can maintain 125 mph with only 4500hp, I fail to see why a 180 has to have 3750hp installed for only 5 vehicles.

Edited June 17, 2017 by jonny777

[St. Simon]

If an HST with 10 vehicles (2+8) can maintain 125 mph with only 4500hp, I fail to see why a 180 has to have 3750hp installed for only 5 vehicles.

 

Hi,

 

The 180s were originally used on Cornwall services I think (or were envisaged to), and the steep gradients and start stop nature of the line West of Plymouth means that actually they are not that under powered, and the HSTs tend to struggle on the gradients if it's a busy train and slightly wet.

 

Now, they are being used, on the Western, for the Cotswold Services and some Oxford - Padd stoppers, the Cotswold line is stop start with single track in places, the so the extra power to accelerate with a heavy train is needed to prevent delay as with the Oxford Stoppers, you need to get to Hayes from Reading at the time your meant to otherwise you'll get stuck behind a Heathrow unit. 

 

Also, remember some of that power (granted not all that much) is going to powering the trains systems which require more power than an HST due to the additional computers etc.

 

Simon

[Edwin_m]

I think some here are confusing power with tractive effort. 

 

At low speeds the power available can't all be used, otherwise it would just spin the wheels.  Acceleration and hill-climbing at these low speeds are principailly determined by the proportion of the train's weight that sits on powered axles, plus whether there is any creep control or other clever system that allows adhesion to be used more effectively.  As speed increases power starts to make a difference, so typically when accelerating from a stop a suburban DMU will outpace an HST initially but the HST will overtake somewhere down the line.  Sprinters, Voyagers and 180s have 50% of their weight on powered axles, it's about 33% for an HST and lower still for an EMU of classes 317-322 or 455 where only one car is powered but it's a bit heavier than the other three. 

[jamie92208]

I think some here are confusing power with tractive effort. 

 

At low speeds the power available can't all be used, otherwise it would just spin the wheels.  Acceleration and hill-climbing at these low speeds are principailly determined by the proportion of the train's weight that sits on powered axles, plus whether there is any creep control or other clever system that allows adhesion to be used more effectively.  As speed increases power starts to make a difference, so typically when accelerating from a stop a suburban DMU will outpace an HST initially but the HST will overtake somewhere down the line.  Sprinters, Voyagers and 180s have 50% of their weight on powered axles, it's about 33% for an HST and lower still for an EMU of classes 317-322 or 455 where only one car is powered but it's a bit heavier than the other three. 

 

That is apparently where the DfT got confused about the law of physics.  They specified lots of powered axles so the initial acceleration for an 800 is very good up to IIRC 20 mph after that Physics re-asserts itself and grunt is needed and there apparently isn't enough of it.   

 

Jamie

[Coryton]

Hi,

 

The 180s were originally used on Cornwall services I think (or were envisaged to), and the steep gradients and start stop nature of the line West of Plymouth means that actually they are not that under powered, and the HSTs tend to struggle on the gradients if it's a busy train and slightly wet.

 

Now, they are being used, on the Western, for the Cotswold Services and some Oxford - Padd stoppers, the Cotswold line is stop start with single track in places, the so the extra power to accelerate with a heavy train is needed to prevent delay as with the Oxford Stoppers, you need to get to Hayes from Reading at the time your meant to otherwise you'll get stuck behind a Heathrow unit. 

 

Also, remember some of that power (granted not all that much) is going to powering the trains systems which require more power than an HST due to the additional computers etc.

 

Simon

 

Likewise I would imagine that Cross-Country services would be more likely to need good acceleration than the ECML and GWML services that the HST originally ran on.

 

If I remember correctly, when Voyagers were being introduced there was talk of retaining some HST sets, cut down to 5 coaches because at full length they wouldn't be able to keep to the new timings due to their lower acceleration.

 

As the railways have become busier I think the game has changed from basing power on what is needed to maintain maximum speed to looking at what acceleration is required.

 

Someone who knows more about diesel-electric and diesel-hydraulic engines and transmissions can tell me if giving a train more power makes it less fuel-efficient when at a steady speed.

 

Clearly with electric transmission it could be arranged so that one or more engines are shut down when not required, and I think I've read that this is done on 185s.

[robertcwp]

 

 

Clearly with electric transmission it could be arranged so that one or more engines are shut down when not required, and I think I've read that this is done on 185s.

185s are diesel-hydraulic.

[Coryton]

185s are diesel-hydraulic.

 

So they are.

 

Well you can still shut off one engine of course....

[Zomboid]

Definitely some fittings inside the span over 1&2 at Paddington. Some new copper span wires at the bottom of the arch of the roof, presumably they can only be linked to electrification.

[The Stationmaster]

As a matter of interest does anyone know if the sort of webbing strap used for lifting and securing loads can become a conductor if it gets wet?  The only reason for asking is that there is some tied round a 25kv feeder near Scours Lane and the other end is resting on the (earthed) gantry structure.

 

On the other hand I am already sufficiently knowledgeable to know that attaching a 25kv contact wire to a structure without an intervening insulator will have an interest effect on the circuit breakers when power is turned on  (there is an insulator - off to the right out of view) in the catenary wire but the last time I looked the contact wire had still not acquired such a potentially useful accessory.

 

[Edwin_m]

There were some photos posted somewhere of OLE in Glasgow without insulators.  I think if they run out of time they just secure the wire direct to the support and come back later to cut it back and insert the insulator. 

[jim.snowdon]

There were some photos posted somewhere of OLE in Glasgow without insulators.  I think if they run out of time they just secure the wire direct to the support and come back later to cut it back and insert the insulator. 

Granted, if for unforeseen reasons you run out of time, the priority has to be leaving the job in a part-finished but safe state so that the railway can be handed back to the operators. However, these days it seems all too common for jobs to be half done for want of planning, or parts and an attitude of "it'll be picked up as part of snagging later", forgetting that it is cheaper and simpler to get the job done right in the first place. But, a job that is done "with snags" is a tick on the progress chart, whereas a job not completed for is not. I had exactly the same when I was involved with getting Croydon Tramlink built, with a contractor whose attitude was "just get it built, we'll put it right afterwards".

 

Jim

[Zomboid]

On the other hand I am already sufficiently knowledgeable to know that attaching a 25kv contact wire to a structure without an intervening insulator will have an interest effect on the circuit breakers when power is turned on (there is an insulator - off to the right out of view) in the catenary wire but the last time I looked the contact wire had still not acquired such a potentially useful accessory.

Not that interesting really, just a bang if you're close enough to hear it. That's probably a good enough connection that you wouldn't even get any sparks at the earth connection.

DC switchgear is much more fun

[HillsideDepot]

Not directly "on topic" for electrification, but closely related to it as rolling stock is cascaded, I was amused by this line on a GWR news story about the 165s entering service on the Severn Beach line. 

Later in the year, we’ll do the same in the wider Bristol area.

Presumably the "wider" Bristol area to allow for the larger loading gauge of the 165/166 vehicles  .

 

More seriously, the Thames Severn Turbos have been modified to increase their ride height to achieve the required clearances and are now not permitted to couple to their unmodified brethren. Perhaps it's time I revisited "the Beach", last time I did it, it was on a Bubble Car and we alighted at Lawrence Hill on the way back to visit Max William's model shop a few doors along from the station...  

[Coryton]

Not that interesting really, just a bang if you're close enough to hear it. That's probably a good enough connection that you wouldn't even get any sparks at the earth connection.

DC switchgear is much more fun

 

A squirrel climbing into a transformer can be quite dramatic.

Not directly "on topic" for electrification, but closely related to it as rolling stock is cascaded, I was amused by this line on a GWR news story about the 165s entering service on the Severn Beach line. 

Presumably the "wider" Bristol area to allow for the larger loading gauge of the 165/166 vehicles  .

 

More seriously, the Thames Severn Turbos have been modified to increase their ride height to achieve the required clearances and are now not permitted to couple to their unmodified brethren. Perhaps it's time I revisited "the Beach", last time I did it, it was on a Bubble Car and we alighted at Lawrence Hill on the way back to visit Max William's model shop a few doors along from the station...  

 

Hmmm.

 

Will they have a separate column in the sectional appendix?

[Edwin_m]

Will they have a separate column in the sectional appendix?

The reason they are doing this is to get clearance on more routes, so I think they'd have to have a separate column to define which extra routes they can use.  I notice the power-door Mk3s have their own column. 

[Zomboid]

A squirrel climbing into a transformer can be quite dramatic.

 

How would that come to pass? The tank should be sealed (apart from the breather, but that has filters and things).

I suspect it would indeed be quite exciting though. Particularly for the squirrel.

[Northroader]

On the Southern third rail substations they put a plastic eagle owl on top by the transformers, and I suppose that scares the squirrels away. On this GWR overhead scheme, they're not doing that, I suppose it's because they're working to a budget?