Edwin_m

Exeter to Birmingham New Street by existing route. Travelator connection to Curzon Street, train to Toton taking 40min or so less than the existing service to Nottingham. Train direct from Toton to Lincoln. This is of course dependent on things like good links between the Birmingham stations (or even a connection for through trains) and reshaping East Midlands services to provide connections to HS2 without affecting existing journeys. These measures ought to be part and parcel of the scheme to spread the benefits most widely.

As a clarification some passenger trains do have a failsafe parking brake which is applied by a spring and held off by air pressure, but doesn't have enough brake force to be much use in stopping a moving train. Perhaps in time these will spread to freight wagons and this particular problem will go away?

There's another empty Spanish airport at Castellon-Costa Azahar.

I think this is only partly true. Good communications can encourage development of an area but there are always going to be areas which still don't have what it needs even with the best communication possible. Comparing Birmingham with Aberystwyth, the former has a large workforce and many brownfield sites suitable for development, and it is arguable that better communications will encourage economic development with relatively low environmental downsides. Aberystwyth has limited workforce and wouldn't be readily commutable from any larger population centre even with a hypothetical high speed rail link. So any major business development would have to be accompanied by housing, both of which would have to be on greenfield sites in countryside that most people would wish to preserve. Whatever form of transport is used, communication to a more remote centre will be more expensive and environmentally damaging than to one closer to existing centres of activity. So large-scale development in Aberystwyth is unlikely to be acceptable and unlikely to happen. Obviously this is an extreme case but the same will apply to some degree in other places.

If there was demand for more domestic air travel then the market is such that it would be provided - Ryanair manages to do so with a nearly-new fleet. The fact this hasn't happened suggests that either the demand is already satisfied or it is constrained by factors such as runway capacity at Heathrow or other airports that people want to use. I think we would all agree this isn't easy to increase! In the longer term there is the environmental downside of aviation, which is probably worse for short-haul flights because of the frequent takeoffs and landings. There is also the risk of relying too much on fossil or biofuels which could become much more costly in the future, whereas an electric railway can be powered from any energy source (which ones we end up going for is another topic). Plus all the cities on the HS2 phases 1 and 2 Y-network will be within the 3-hour limit of each other, where experience has shown that rail claims practically the whole non-road market because its centre-to-centre time is less than that of air. In any future phase 3 to Scotland, rail speed becomes more important because it allows Edinburgh and Glasgow to be within this limit from London and Birmingham, and therefore achieves real transfer from air to rail.

McLoughlin was interviewed on Sky, saying just that and quoted on Radio 4 news just now.

I'd be interested in seeing any actual evidence that increased access to electronic communications is actually reducing the need for physical travel, particularly of the medium to long distance type that HS2 is aimed at. I was recently at a workshop on a separate high speed project (which presumably makes me part of the gravy train!) where most people seemed to be of the opposite view.

With a 2-man crew the person who stays on the engine can presumably check by releasing the air brakes whether enough hand brakes have been applied (the two crew would be in touch by radio to ensure the one on the ground was clear of the train when this was done). If there is only one crew member they would have to walk back to the engine to do this, before returning down the train to apply more brakes if needed. I can't help thinking that the single crew member makes it much less likely that this check will be done which confirms that enough brakes have been applied for the prevailing gradient, and that they are applied sufficiently hard and working correctly.

To be fair some of the HS2 documentation is hard to find and/or of a technical nature.

Don't forget that we have built HS1 in the UK within the past decade so we should have a pretty good idea of the costs of high-speed infrastructure in an area of countryside that is relatively densely populated and sensitive. Let's not get started on trolleybuses again!

I guess if there was no call after a reasonable time the next train would be accepted but stopped and cautioned to examine the line.

750V is the nominal voltage and the third rail will normally sit at this voltage if there are no trains around (excepting any sections not yet upgraded from lower voltages). There is an international standard on voltage range which I can't easily access at present but it is permitted to vary within quite a large range. Not surprisingly it drops if there are several trains drawing current nearby, but it also rises if trains are using regenerative braking, and the headroom between the nominal and the maximum permitted voltage allows regenerative braking to take place with associated savings in power use. Trains using regenerative braking will monitor the rail voltage and dump the power into resistors instead if it exceeds the maximum.

There is indeed a gap in the supply rails, on Kew Bridge for example and there will need to be another one on the Croxley Link. Undergound trains only have shoes electrically connected within one coach, whereas third rail units have a bus line through the whole unit. As only Underground trains cross these gaps they only need to be one coach long. If electrically connected shoes were simultaneously on the +750V/0V and the +420V/-210V then there would be over 200V across each of the electrical connections and this would (hopefully!) trip the circuit breakers.

Maybe they should put a convenient grab handle on the back corners of the HS2 trains?

If that is the same street then it's downhill both ways (we know streets in t'North only go uphill both ways!). As the road surface, lamps and details of the houses are also different then I think it's two different streets. The architecture of terraces actually changed quite a bit from place to place so may give a clue to those in the know (not me!).

You'd still need a mechanical backup in case the power failed or to apply/release the brakes when not coupled to the loco.

Nothing like that on a tramway, which basically follows highway practice. Crossings on segregated tramways normally just have passive measures, although a red/green man or the obsolete arrangement of orange flashing lights may be provided at particularly risky sites. Having said that there have been quite a few serious incidents where trams have struck pedestrians on crossings and the designers are now much more aware of the issues.

The Value of Preventing a Fataility was around £1.5m at the time of TPWS, based on surveys asking how much of their own money people would be willing to spend to save the life of someone who was not a close relative. It's actually much lower now, I think because there is a common figure between rail and highway which there wasn't at the time. Even at the higher figure TPWS was a bit marginal, and I think some of the extra features added during development probably pushed it over.

A lower speed would not reduce the cost much. The minimum radius would be less but the designers have already had to reduce the speed where it isn't possible to accommodate a 400km/h alignment without unacceptable disbenefit. The fact they have done this in some places suggests they would have done it elsewhere as well if there was a reason to do so. The fact it's mostly designed for 400km/h doesn't mean it will be used at that speed - the published journey times are based on a maximum of 330km/h. The top speed will be chosen nearer to the opening date in the light of train technology, energy costs and the state of competing modes at the time. As I said above there is very little extra cost incurred if the present route ends up being used at a lower speed, but a huge amount extra if a lower design speed was assumed now and conditions closer to opening date suggested that 400km/h was more appropriate.

The GW ATP system was introduced before Southall and Ladbroke Grove. It was isolated on the train at Southall because (IIRC) the driver wasn't trained it its use, AWS was isolated due to a fault so the driver had nothing to alert him to adverse signals. Only Great Western trains were fitted with ATP on that route, so the SPAD by a Thames Trains unit at Ladbroke Grove was not protected. GW ATP is still in use but the decision was made not to adopt either this or the Chiltern system on a wider basis (though it was extended to Heathrow and the Heathrow Express units when that route opened). TPWS was thought up as a system that would address the majority of the ATP-preventable risk but would be much cheaper, easier and quicker to fit. Authorisation was awaiting sign-off by John Prescott's department at the time of Ladbroke Grove. Although the Uff-Cullen report was rather sniffy about it, subsequent experience has borne out the TPWS casualty reduction predictions (which I had a small part in making).

Highway engineers of my acquaintance use "in advance" to mean the opposite of the railway meaning. In my view the frequent transfer of labour between railway and highway contracts makes that one difficult to defend these days.

Well someone has to pay it and if the damage from heavy goods vehicles is indeed so great then it would be a good idea to reduce it. For example would "hub and spoke" be the preferred distribution model if the haulier had to pay a lot more for their mileage? Or should we be going over to concrete pavement?

That has been worked out in the HS2 documentation but I haven't time to look it out now. The junction for any Heathrow branch/loop would be well south of the Chilterns - somewhere near Ruislip I think - so any Chilterns station would be on the main line. Again the Heathrow junction is discussed somewhere in the HS2 documentation.

If road hauliers paid something like their full infrastructure costs then they would be more incentivised to minimise damage to the infrastructure. This might lead to different ways of working, such as use of more sophisticated vehicles that cost more but damage less (as has happend on the railways with track-friendly bogies). At worst the total cost to the national economy would remain the same (the roads still cost the same to maintain but this cost would be paid by users of goods transported by road, instead of being paid by taxpayers - who are largely the same people). If the incentivisation works then the total cost would fall.

You said "airport branch" not "Heathrow branch" so I misinterpreted that. A station in the Chilterns would cost two paths for each train that stops there, unless its stopping service was frequent enough that the path vacated by one stopping train was filled by the previous one accelerating away from the stop. I think we've been though that issue at least once already on this thread. The original HS2 reports made a very good point that no one station would serve all of Heathrow, so if airport passengers have to make a transfer to get to their terminal they might as well make it at Old Oak Common. Changing there would also give a better choice of train and destination on HS2, as there are only two Heathrow trains per hour in the proposed HS2 service pattern. And the Heathrow people don't seem to accept that HS2 avoids the need for the third runway, as they are still putting the runway forward in the full knowledge that HS2 is proposed.