locoholic

25 minutes ago, frobisher said:

 

Wind resistance is proportional to the square of the speed within turbulent flow, with non-turbulent flow it is proportional to speed - and it's somewhere in between for the cases somewhere in between.  Decent aerodynamics will keep it near the non-squared end.

 

When the energy is coming from the national grid, you're more concerned with the rate of power consumption rather than how much energy is used overall (hint, it's NOT a battery).

 

Also, regenerative braking puts a large chunk of that energy back into the grid in any case...

 

Do train companies not get charged for how much electricity they use, like the rest of us do?

With High Speed rail, if you try to limit the power consumption by accelerating more slowly, then you spend much less time at the design speed and therefore derive less benefit from spending all that money making trains that will go fast. Or, you can skimp on the design as well, and have traction motors and OHLE that can't deliver rapid acceleration, but journey times will be compromised.

i'm not against High Speed rail. I just don't think it's honest to present it as being no more financially or environmentally costly than conventional rail.

1 hour ago, Mike Storey said:

 

So the argument shifts yet again. Brand new faster trains, without tilt, and lines, are not significantly more expensive to build or operate. What makes them expensive is having to cope with more than one electrification and signalling system, which would be the case at any speed. There is a case that tunnels and deep cutting profiles for high speed present additional design costs, and foundations in certain geology, but the Japanese have rapidly progressed knowledge about this in the last decade, which is where I am sure HS2's consultants will be looking to for help. Alstom are now building double deck TGV sets for SNCF that are half the cost (in real terms) than their forefathers. You really need to check what is happening elsewhere, and what the conclusions of the original studies between various line profiles showed cost-wise, before making grand assumptions resulting in false conclusions.

 

I do not challenge the fact that extra energy will be necessary for higher speeds. But if there is no economic case for so doing, why is everyone else doing it??

 

Just read back through your comments and see how many times you have introduced irrelevancies and "shifted" the argument. Why is everyone else doing it? That's another question entirely, but you can be sure that they appreciate that the costs escalate exponentially as the design speed increases.

44 minutes ago, Mike Storey said:

 

No, you won't, not least because someone has pointed out that your knowledge of applied physics may not actually be correct in this case. Most long distance trains spend a large proportion of their journey coasting anyway, once top speed has been achieved, but you were not to know that either. But, whatever, when you continue to only count energy consumption as the primary cost, then you will never persuade anyone who has any knowledge of the real, total costs of running a railway. Full Stop.

Your argument relies totally on the fact that higher line speeds mean that a slightly smaller fleet of trains is needed to transport the same number of passengers. You think that saving cancels out the fact that faster trains and lines are significantly more expensive to build, operate and maintain. It does not. Full stop.

7 hours ago, frobisher said:

 

If you're thinking 1/2 mv^2 then go and sit at the back of the class... That's the equation for kinetic energy (for twice the speed, this quadruples).  This is NOT a continuous energy input, but merely the potential energy of the object due to it's velocity relative to a stationary object.

 

In simple terms, it takes quadruple the energy to get to the top speed.  If it does so over 4 times as long as the similar massed train does to get to half the speed then the average instantaneous power consumed (i.e. the draw from the OHLE) is in fact the same over the acceleration.  When at speed you're "just" looking at factors such as rolling resistance (which is proportional to velocity), air resistance (which is mostly proportional to velocity,  etc for the power inputs (these are of course non trivial in reality) .  So probably nearer double than quadruple.

 

Yes, I know, although the wind resistance is proportional to the square of the speed.

Not sure what your point is about power consumption. If the train has a higher operating speed, it uses a lot more energy to reach that speed.

In the timelapse film the sleepers look wooden, not steel.

25311 and 37015 on a Freightliner approaching Saltley, Birmingham, 13 October 1982.

50 minutes ago, Mike Storey said:

 

some things - and also fewer trains and fewer crews to staff them all. Rather cheaper I think.

 

The French have never gone for high utilisation of their train fleets, until some recent eureka moment, involving their OuiGo sets. The higher speed trade off does not seem to bother the Chinese, Koreans, Japanese, Italians and Germans. Distances between major centres in at least three of those are very comparable to the UK.

Seeing as you think that I made an "error" by knowing that trains obey the laws of physics, I am never going to persuade you that there is no way that it is either financially or environmentally cost neutral to operate a very high speed railway compared to a conventional one.

1 hour ago, The Stationmaster said:

Quite agree about speed and stock utilisation plus unless the train designers have discovered something which SNCF hasn't been able to discover (and knowing SNCF I don't necessarily discount that possibility) the simple fact is that power consumption increases massively at speeds of =200mph and higher.  TGVs could operate in normal service at speeds a bit in excess of =200mph but SNCF don't run them at that speed because of the massive increase in power consumption which would result (one past SNCF colleague said to me that it is nearer 50% than 25% but he wasn't an egineer and I don't know the source of his information).  

 

I appreciate that the TGV is basically 1960s/70s technology and thus somewhat dated but I  do wonder if efficiency gains reducing power consumption at higher speed have been sufficiently significant to make a major difference to energy costs.

Quite agree. As I mentioned previously, the energy requirement is proportional to the square of the speed, so higher speeds require a massive increase in power input. No amount of clever engineering can overcome the basic laws of physics. You can't get something for nothing, the something in this case being shorter journey times.

26 minutes ago, Mike Storey said:

 

Are you assuming electrical energy sources have remained as environmentally damaging as when you learnt that equation? Perhaps that might be your error.

 

The carbon footprint of UK generation has been constantly falling for the past decades, with gas being the primary carbon fuel remaining, bar the few coal fired stations still in use. The increasing probability of much more efficient fuel cell storage will make wind and solar power etc, much more practical in future years. It supplied over 50% of the UK's energy needs on one day last year. That is predicted to become a more normal event, unless HMG policy radically changes.

 

The reason I state environmentally neutral is because the environmental cost of building twice the number of trains is demonstrably higher both at construction and ongoing maintenance/refurbishment, than extra electrical power used in a greener future.

 

HS2 will use electric trains. If you have already expended considerable other types of environmental damage in building the track and the power lines to get to it, plus an OLE system, you might as well run them as fast as you can, if there are other environmental advantages to be had, particularly attracting modal transfer.

1. Historical decreases in the cost to the environment of electricity generation are irrelevant to any discussion of the optimum speed for a new rail service.

2. The source of future energy supplies is also irrelevant, unless you are suggesting that some miraculous free electricity supply will be found.

3. You have not taken account of the greater wear than higher speeds inflict on both trains and track, thus reducing any saving due to the smaller fleet size.

4. The environmental cost of train construction is spread across the lifespan of the train. The longer the train is in service, the better it is for the environment. However, the longer it is in service, the more energy it will use. The faster it goes the more energy it will use, in proportion to the square of its speed, so the initial "saving" in building a smaller, faster fleet becomes less significant over time.

5. You are arguing that a higher line speed (and therefore shorter journey times) can be had without additional cost, either financially or to the environment. This is simply nonsense. There is nothing special about electricity and there is nothing special about trains. They are just machines. I suspect you wouldn't argue that because the car and the motorway have been built, you might as well drive as fast as you can because you won't use any extra petrol and your car won't wear out faster. Exactly the same laws of physics apply to trains.

8 minutes ago, Mike Storey said:

 

The case for higher speed is largely in the fact that fewer trains are needed to perform the same service (up to a theoretical design maximum), so environmental costs are neutral, alongside the additional factor that a faster service is demonstrably more attractive, and more likely to generate modal shift from road and air, again giving environmental benefit.

 

I suspect that your argument conflicts with the laws of physics. The energy required for any moving object is proportional to the square of its velocity. So if a train goes twice as fast you need half the number of trains to run the service, but four times the energy - how is that environmentally neutral?

23 hours ago, caradoc said:

I regularly travel between Oxford and Glasgow, which at present requires a Voyager to Birmingham (International or New St) or Wolverhampton, then what is effectively a 'local' WCML service forward. A sub-50 minute run to Old Oak Common with a reasonable connection to a very fast (at least on HS2) train to Glasgow would be a most attractive alternative.

I wonder how the cost will compare for a journey via OOC that is significantly longer than the route via Banbury?

Then there is the "carbon footprint" of using a route that is much longer and entails you whizzing along HS2 within a few miles of the city where you started. So much for rail travel being environmentally friendly.

This mentality of a "one-HS2 fits all" reminds me of Dr Beeching's attitude to route rationalisation: only one Anglo-Scottish line required, no cross-country routes needed as everyone can travel via London, etc, etc. And we've been paying the price for that mistake for the last 50 years.

I think the most fetching red loco is the LMS Patriot - very well proportioned. Choice of Hornby or Bachmann, too.

It would be interesting if Hornby could sell replacement Class 31 chassis. I would have thought there was a market, but what do I know?

Bachmann used to sell chassis that would fit the old Mainline locos, but they claimed they didn't sell. They were pretty hard to get hold of, so I suspect it wasn't a fair test.

Of course, it would be nice if Hornby made a few more of the "missing" body style/livery combinations, too. In my opinion they have not done a very good job of maximising income from their investment in Class 31 tooling.

PS: is there a train, trapped by buffers at Ormskirk and Kirkby, shuttling to and fro, with no means of escape, I have to ask?

You are describing the erstwhile Waterford and Tramore Railway in Ireland!

A new missive has arrived from the East West Rail Consortium:

 

https://mailchi.mp/b25587a778e1/bedford-cambridge-route-options-announced?e=ddca3c6ce6

 

This considers the route options for Bedford to Cambridge and it seems that a route via Sandy/Tempsford  is preferred.

 

Not strictly Oxford to Bletchley but I can't locate a thread for the whole route. This project has another good ten years still to run so we either add to the existing eighteen pages or start a new one!

 

David

Route A is cheapest and most direct, so that one's ruled out.

Put the turbines close enough and the turbulence would blow them round .

And if the train roof had solar cells.....

 

Better yet, put a gym in one coach and the exercise bikes could generate electricity

Why not go the whole hog and put small wind turbines on each train? A perpetual motion train - you know it makes sense.

The government tries some joined up thinking - again?

"We apologise for the late running of this train. This is due to the wind dropping unexpectedly."

... People have been removed from railway lines precisely to reduce the numbers of people at risk...

If they removed the trains as well then the risk would disappear altogether, both for rail workers and passengers.

I hesitate to be so flippant, but when any problem is approached using dogma rather than rational thought, odd results often occur. And the recent results in terms of rail project delivery have given some very odd results.

"30-420 Western Pullman - Dynamis Ultima Sound Fitted Train Set £949.95"

That's got to be a typo! You could go on holiday for less than that!

Not a typo, I fear. Just an error of judgement, in my humble opinion.

The newspaper report seems to suggest that the trains kept running! What an amazing story.

Saw this on Facebook! US blues singer perfoming on the platform of what looks like a railway station in England, with the audience on the opposite platform.

Does anyone know when and where this was? I guess it was on a Sunday at a station with no Sunday service!

I can't figure out how to put a link to the video footage, so here is a screenshot.

Excellent. Some inhabitants for the lovely NER shed that TMC sell.

I would love them to do a "classic" 1950s Woolworths.

I also wondered whether Hornby could team up with the National Trust - not all of their buildings are massive stately homes.

Some more variations of the N7 would be nice: late BR crest, the blue Liverpool St pilot one, etc etc.

A couple of GER coaches, perhaps? Looking through the 2019 Roco announcements I was quite jealous of how "joined up" their range is, with matching locos/coaches/wagons.

Who knows - they might even do a Class 120 DMU?!