Captain Pegg

They won't. That assumes 14 double length trains run every hour for over 20 hours of the day, 7 days a week, and that the load factors are 100% for every train. That won't happen and it doesn't need to. It's your business whether you support the idea or not and you don't have to justify your view to me or anyone else. Just that if you want to discuss the merits in a serious way it needs objective analysis and facts. A bit of knowledge and experience helps too. I acknowledge your 40-67% electricity statistic has provenance. It is though a commercial document it comes from. I still can't come close to reconciling it with a basic calculation of fleet and network sizes of HS2 and the conventional network though, even when using the comparative numbers in KPMGs report. Still, it remains a fact that HS2 will need a lot of power (unless of course no one turns up to use it). Agree we should go and post about boating. JP

With the bridge in question in the background. By 1976 the generating plant would have been closed. The cooling towers were demolished probably in the late 70s (1980 at a push). I remember lessons being stopped at school so all the kids could go out into the playground and watch. JP

I only quoted numbers of direct journeys between London Euston and Birmingham New Street, and London Euston and Manchester Piccadilly in order to demonstrate that were thousands of people wanting to make that journey each day in response to you questioning the demand for such. Those are the largest long distance flows from London Euston but they only represent about 10% of the overall numbers of people using the routes out of Euston station. HS2 Ltd has stated that it will have increased capacity but it is essentially a replacement for both West Coast and East Coast main lines once Phase 2b is built.That additional capacity is nothing like the number you have calculated. JP

The figure came straight out of my head from memory. If you want to form an understanding of the issues behind the idea for HS2 search on "West Coast Main Line Route Utilisation Strategy" and you will find a document published in 2011 which will give the background to the challenges that created the idea for HS2. It also contains passenger numbers for 2009/10 in Table 3.9 on page 47 which were 2.7m London to Manchester and 2.3m London to Birmingham and growth at 5% year on year. Work it out and you should get to something in the order of 20,000 passengers per day currently. All major transport projects have an environmental impact; always have had and always will do. If you want to address the demand for travel then rail is generally a more friendly way of doing it than the alternatives. It's perfectly fine to want to suppress economic growth in favour of protecting the environment but I don't think it's where society is at as a whole. Your argument is more against the desires of society as a whole than against HS2. JP

Demonstrating demand is the easiest bit of the equation. There's broadly 20,000 direct journeys between London Euston and Birmingham New Street or Manchester Piccadilly every day now. There are three trains an hour for 16 hours a day, 7 days a week to both Birmingham and Manchester from London. The passenger numbers have doubled over 20 years at the same time that road usage has also increased and all despite (or perhaps in part because of) the boom in mobile communications and agile working. All future forecasts say demand for travel will continue to grow, the only real debate is by how much and how to solve the demand it brings. The alternative is to accept the UK will stagnate economically and we all become relatively poorer. The scope of HS2 will link the centres of five metropolitan areas totalling 20 million people (one third of the UK population) with journey times of 45 to 90 minutes. There is over 50 years of evidence from around the world of the impact of doing that kind of thing. So there is a strong degree of certainty over the likely outcome. There is proven technology so providing the right specification and procurement strategies are put in place the risks are quite low for a project of such magnitude. The chances of it being a white elephant are pretty much nil. That hasn't happened in Japan, Germany, France, Italy, Spain or indeed in the South East of the UK where we already have HS1. These places have been building high speed rail for half a century and continue to expand their networks. The Chinese will trump all of the combined achievements of the rest of the World in terms of scope of operation if they haven't already done so. What is it about the UK that is different? Also, have a think about your 40-67% power consumption increase figure. Moomin Papa has given you the demand required by the HS2 fleet so now go and research the demand of the existing electric train fleet of the UK and see if even your low end of 40% can realistically be anywhere near accurate. My personal view is that London to Birmingham is the obvious starting point but the real goal is to link all those cities directly and the UK will feel the benefit as a whole once the gaps between Liverpool, Manchester and Leeds are closed. There is a risk of a brain drain effect by better connecting provincial cities to London but not to each other. To realise the benefits we need to get on with and do it properly. JP

The photos and map suggest that maybe the particular bridge in question was a later addition. The style also made me wonder if it was a cable bridge rather than a footbridge. JP

It hasn't arrived at my house; nor will it. I don't subscribe.

That's a pretty impressive feat considering there appears to be no continuous standard gauge route from China to London. A direct service involving a couple of transhipments of the containers is probably closer to the truth. The first train of this nature was a couple of years ago now. JP

No. Presume that should be Canal Boat (magazine)?

Thank you MP, I did wonder about frequency and phase but it’s not my area of expertise. To be fair to George I support his point it’s just that I believe some of the stuff put out there is misleading and if we want a proper debate of the merits of building HS2 we need proper facts from all sides. One particular use of energy recovery currently being trialled is on board battery storage which gives the capability to either reduce the overall power demand or allow discontinuous electrification so that discrete difficult, expensive to electrify sections can be omitted from an overall scheme. There is still the issue of lugging the weight around which fundamentally undermines the purpose of electrification. JP

Another person not specially mentioned above;- Peter Tyler, son of William and Mary (nee Woodsby), born 1892 at Market Drayton, died 15 Dec 1917 and buried at Thiepval. Seemed to have lived his entire live on board boats prior to service. JP

Supply is 25kV 50Hz AC on the overhead system but historically transformed and rectified to 1500v DC onboard the locomotive. Pretty much all UK mainline electrification pre-dates regenerative braking so it would never have been a consideration. I will consult some folks who will know what modern technology can and does achieve now there are AC traction systems available.

The sections are about 15 miles each. You've missed one just south of Euxton. Catterall feeds northward to Hest Bank. Euxton Jn to Catterall is fed from a feeder at Euxton. Golborne to Euxton is fed from a feeder that I think sits at the intersection of the WCML and Liverpool & Manchester Railway. The next section to the south is only 12 miles and covers Preston Brook to Winwick. Improving power supplies for increased demand needs shorter sections. The limitation is what the grid can supply. It's one of the capacity constraints that is often overlooked when considering the ability to run longer trains; along with things like platform length and pedflow capability of stations. Energy is recovered, I am not questioning that. I am just sceptical that as much as 20% of that drawn for power is usefully returned. That's a very big number when you consider the relatively small proportion of time a train will spend under braking compared to drawing power and that the energy created has to be used instantaneously. Does your source have good provenance? On HS2 I would also expect the potential for recovery to be lower than the conventional network due to less need to brake. JP

Can't beat some proper scientific fact. Anyway, something has to provide a base load for the new nuclear stations. JP

It's true that if the same number of trains run between the same points the overall power draw for making them go faster will be greater. The balance lies in that the faster the journey the more demand is created and more income to pay for it. Overall this generates a better business case for making it high speed. Technologically there isn't a major step change from conventional to high speed rail. There is a couple of centuries of evidence to demonstrate the economic impact of rail infrastructure projects in the UK and 50 years of high speed rail on our doorstep. It's not high risk providing the country holds it nerve and gets on with it. Delays and scope changes will damage the case. If you were asked to build a railway from A to B would you deliberately make it less straight if the required speed was lower and the curves could be sharper? I think no matter the technology the starting point for a potential route is a straight line. JP

That energy can only be put to useful work if another train is drawing at least as much power in the same electrical section simultaneously to one that is using the regenerative brakes. If 20% is correct I suspect a good deal of it is dissipated from the overhead wires as heat. That old Virgin Trains TV advert about putting enough power back into the 'grid' to boil however many kettles was very cleverly worded to satisfy the ASA. There is no means of back feeding the National Grid. JP

I will gladly do that In the case of an engineering project it is the consultant that is being consulted (by the client). It is the client's job to determine the requirements. From an engineering perspective it all looks fine to me and I've dealt with similar failures in my own line of work. JP

I'm not trying to help you see the advantages; I haven't advocated any form of zinc coating. My point is that crap evidence and misunderstanding of the science isn't helpful to anyone trying to make a decision. I agree pitting is a greater threat although in most cases likely to be a result of specific chemical attack than dissimilar metals. JP

Hot dip galvanising should provide a better bond and have better galvanic properties than any other available zinc coating. However that's a moot point because you can't hot dip galvanise a boat. Any barrier between two dissimilar metals will prevent galvanic corrosion. That's simply done by forming a water tight barrier so in essence 2 pack epoxy and bitumen protect in exactly the same way as hot dip galvanising or molten zinc spray. They just lose that protection when damaged but zinc based products retain a degree of protection. Where the balance lies I don't know. It would take testing over time to establish that. As for over coating the zinc spray with 2 pack I can't help but wonder if the 2 pack would perform better if it were directly bonded to the hull. JP

The subject is the coating of hulls and the specific analogy you used was the galvanising of garden furniture. All metals have a degree of "floating electrical worms" assuming what you are actually talking about is free electrons. That why they have galvanic properties that vary according to the number of free electrons. So anything that is galvanised has free electrons in its coating. That isn't a problem; it's the intention. The stuff above is about protecting dissimilar metals which obviously involves the use of sacrificial anodes. The complete coating of hulls - or any metal object - with zinc based products is done for a different purpose. JP

Yes. It's just a protective layer to prevent the parent metal from corroding as it would if it was open to the environment. The galvanic bit only comes into play when the coating is damaged as it continues to protect across minor breaks in the coating in a way that a conventional paint based protective system can't do. Additionally hot dip galvanising offers better protection than hot sprayed zinc or cold applied zinc rich paint in such scenarios. You seem to labouring under the idea that because it is galvanic then it is somehow only applied to prevent galvanic corrosion. JP

If they are not submerged they are not galvanised in the normal sense of the term. As for "loose electrical worms" what does that mean? Galvanising isn't "for" cathodic protection, it IS cathodic* protection (against rusting). * - do not write in and tell me it's anodic. It's electrolytic protection in principle. JP

All coatings are sacrificial, just by different mechanisms. That's why they all have a shelf life. It's a personal choice as to what method and unless we want to apply some science above primary school level we will never know for certain which is best. I already answered your question above in my first response to the original question. That coating will still degrade though. JP

Because it prevents the thing you are protecting from eroding. All coatings have a shelf life. Not a massively relevant question. JP