david.hill64

Which is why modern WSP systems try to control wheel speed in braking so that it is almost synchronous. A small amount of slippage has a conditioning effect on the wheel-rail interface, cleaning it and improving adhesion. The downside of small creep values is that the largest tangential stresses in the contact area occur just sub-surface of the interface. This promotes rolling contact fatigue damage, hence we now grind rails to remove the damages surface layer before the cracks can propagate.

IIRC the BT5 was a heavyweight version of the BT10, also used on the 'special vehicles' (Royal Train) project.

I think it is a BT15*. I remember riding in a test train with one of the coaches fitted with this bogie and seeing the look of disappointment on the face of the bogie engineer responsible for the project as the ride was, shall we say, disappointing. Mind you it was very difficult to match the ride of a BT10 when the dampers were in good shape. The vehicle was in the train as a make weight rather than being the primary focus of the tests. * When I saw the photo BT 15 was my first guess, but there were other similar developments that tried to eliminate the panhard rod assembly of the BT10, so I may well be wrong.

No. The main reason why outside bearings were standard was for hot box detection when this was a real issue. Moving the bearings inside results in a significant weight saving. Primary suspension design is mostly about wheel-rail interaction (steering). Softer secondary suspension will give a better ride at the expense of body movement which has to be restricted to comply with gauging requirements. I suspect that this is the reason why we notice poorer ride, though the dreadful tertiary suspension (seating) doesn't help.

When the Hymeks were being withdrawn I had a week in Scotland planned which started with a late evening departure from Gloucester to Birmingham. I was very happy when the Cardiff to Birmingham train arrived at Gloucester Central behind a grubby looking Hymek. I thought I was in for a treat with a thrash up the Lickey. Sadly the Hymek was removed, but was replaced by a pair of 25's. Never regular performers on passenger trains through Gloucester. Made for an interesting start to the week.

Suggestions from letter writers in the Telegraph today suggest that capacity on the existing lines can be made available by running double deck trains, lowering the track through tunnels and at bridges if there isn't sufficient headroom. Another pundit suggests running trains closer together using LIDAR so that they can almost buffer up when one has stopped.

The company I work for now is bidding to support a Japanese company for a job on a local HSR project. The Japanese have made it a condition of contract award that there shall be no involvement of any of my company's China personnel. They are still bitter at the theft of IPR and don't want to get bitten again. I am used to non-disclosure agreements but the Japanese are now taking this to a new level.

I was one of them. At the time - 20 years ago - my flights to and from Taiwan were mostly with EVA air. Pilots were inevitably western. China Air (the Taiwan national carrier) used ex military pilots and had a rather poor safety record. EVA management understood that they needed to instil a different culture in the cockpit crew and that would take time. These days most of the EVA flight crew are Taiwanese.

If it is a new Jag it will be a diesel hybrid. Still have waiting times of 6-9 months on most models.

That's because the design of the Shinkansen Electrification system cannot cope with anything more than 80km/h on the diverging route. Pantographs have to be strong as the horns are use to guide the head at diverging locations. Doing this at high speeds is likely to interfere with the knitting. I worked on the Taiwan High Speed Rail system, the infrastructure design for which was based on UIC standards. The alignment had been optimised to allow skip-stop operations including long turnouts with a 200km/h diverging speed limit. The Japanese were unable to take advantage of this. The Japanese have standardised turnouts - quite sensible really. Of course my experience is 20 years old now and they may have changed but I think it unlikely as they stick with things that work.

But temporary: there will be a net gain in woodland once finished. I know that 300 year old woodland will take a few years to re-establish, but this project has been very mindful - perhaps too minful? - of ecological consequences. What would you have done instead? Stop people travelling? We have an aging and growing population. Both older and younger people are less inclined to drive than previous generations. Do you stop them travelling, or do you provide them with a modern efficient transport system?

The project is littered with scope changes, mostly for political reasons. Tunnelling under the Chilterns is an obvious one, as is the indecision about Euston. Contractors make their money on changes. As the boss of Met-Cam said: changes turn a net loss into a gross profit. George Osbourne asks the question 'why does it cost so much more to build a railway here than in continental Europe?' It's a valid point but I doubt whether the construction costs are very much different. It is the plague of parasites that feed off every major investment opportunity here.

Just had chance to watch this. I thought it was thought-provoking and interesting, apart from the cheap political shots, but I guess they were inevitable. When he discussed the winners from privatisation he forgot to mention staff, especially drivers whose remuneration is considerably better than it was before. No mention either of the (until recently) significantly increased level of service or safety improvements, and how running too many trains on a network inevitably leads to problems when things start to fall apart, nor of the fact that when Labour were in power they did nothing to reverse privatisation of the TOCs. I think that the points about Leamside and Castlefield are particularly telling. London got Crossrail - Manchester gets little.

Just following up on private sector involvement: I was involved with the Taiwan High Speed Rail project in 1992/3 when it was a government funded project. Compared with western countries, Taiwan's government is awash with cash, but still decided in 1993 to cancel the project for affordability reasons. What they did next was to enact legislation that permitted private investment in infrastructure then let a competition to award the project. Knowing that the base economics of rail don't work in favour of the railway (who don't get the larger financial rewards), they sweetened the deal by giving sole development rights in the new station areas for 50 years. So why don't we say to developers/ pension funds/ insurance companies, you pay the cost of the Euston extension, and in return the station site is handed over to you for 50 years. Develop it as you will, get the revenue from offices, retail and £x a head from every passenger. See if the numbers stack up.

So why not use your noddle and invite in the private sector? They are likely to end up buying the infrastructure anyway. It needs something other than groupthink to move forward. Your post is an excellent example of why we don't do things like they do in Asia: we find reasons not to do things. In Asia they find ways to do things.

And this, I think, summarises why so many government departments are inept. Group think is the only opinion tolerated, when what is needed for an effective business is a diversity of opinion and the odd maverick. Dominic Cummings was right when he sought to recruit misfits into government. HS2 will start returning money only when it is up and running. Delaying the project intentionally not only increases costs but delays revenue and runs the risk of being a massive financial burden if cancelled. It needs some brave souls in the civil service to stand up for this.

Unfortunately the idiots in charge are not elected and any change of government is unlikely to make any significant difference.

Power station fly ash was the preferred stuff, but with the absence of large scale coal fired stations, that is going to be hard to come by. I did read that although contractors declared that they had used the designated fly ash in the slabs used on China's HSR system, the tonnage used exceeded the output from all of China's vast number of coal burning stations. The implication was that the slabs would not last their design life.

With the exception of the GPS and cab forward, what you describe is a Shay on the Taiwan Alishan Forest Railway!

Most of HS2 is slab track, so ballast requirements will not be huge.

With the suggestion that either they didn't know what they were doing, which is scary, or they did, which is worse.

Possibly getting regulatory approval would be too much trouble for a trial? Not from the railway side, but from whichever government department authorises telecoms systems. Getting approval for radio systems for railways has always been a hassle wherever I've worked.

The tide took us that way................

For me it was the suggestion that someone might have been depositing copper to hide the cracks that was the most worrying.

Ninth largest manufacturing economy in the world with an output value of £182bn. Largest segment is transport (cars, engines, jet engines) followed by chemicals and pharmaceuticals. Machinery (JCBs etc) also important.