Edwin_m

Interesting thought Mike but I'm not sure I agree. Level crossings have risen to the top of the list of risks because introduction of TPWS and various other measures have pushed SPADs well down from the top position. I don't recall any accident for many years where lack of block controls was contributory, whereas fatal level crossing accidents are all too frequent. Absolute block will be largely eliminated within the next couple of decades with the busiest sections where it is still used probably going first. Although the victim is sometimes to blame, Moreton-on-Lugg demonstrates that isn't always the case, and the fact remains that if the railway wasn't there there would be no accident so (donning a tin hat) I'd suggest there is a degree of moral responsbility to protect road users from their own stupidity. Just as when driving on the road you will do your best to stop if someone runs out in front, and would share the blame if you didn't, even though any impact would be considered to be primarily the pedestrian's fault. Over the past few years we've had level crossing accidents where the train has been derailed, usually if a particularly heavy road vehicle is involved, but fortunately only at low train speeds so resulting in few casualties. Hixon, Lockington and Great Heck demonstrate that a road vehicle collision (not necessarily on a level crossing) has the potential to produce the same sort of casualty numbers as a serious train collision. Although things were done to address the causes of all three, there is still the scope for a series of unlucky coincidences to result in a similar event.

True, but the statistics do show that full barrier crossings are much safer than the various automatic types and indeed half barriers are much safer than lights with no barriers. I agree there is potentially a big issue with user-worked crossings simply because there are so many of them.

As hinted by Gary above, full barrier crossings are always monitored and an operator (or in more recent installations a radar-type detector) confirms that the crossing is clear before the signals are cleared for a train. Therefore there would have to be a failure on the part of the railway before someone trapped between full barriers can be struck by a train. However someone jumping over or crashing through the barriers after the signals have been cleared would not be protected in this way. This has the side-effect that the crossing stays closed to the road a lot longer than a half barrier, because it needs to be closed in time for the train to get a clear run through on green signals.

We've been here before. http://www.rmweb.co.uk/community/index.php?/topic/33312-mk1-ck-coach-windows/ As I understand it, it was for routine transport of people in stretchers rather than any kind of emergency access. This doesn't seem to have been very common and with the advent of better road ambulances and better roads it presumably stopped being needed quite soon afterwards.

You'd need a vehicle of the right "gauge" and steer very carefully to stay between the guides. I suspect they were referring to the damage that might result if a lorry tyre rode over part of the guideway, possibly leading to a bus "derailment".

They would have the facility to replace the signal on the approach side of the crossing to danger even if it normally works automatically. I guess the standard procedure would be to replace this to danger and keep it so until someone could get to the crossing and work it via the local controls. It would probably still be necessary to stop each train at the approach signal to get confirmation from the person at the crossing that the barriers are down.

The full barrier crossings are interlocked with the signals so if the train is to have a clear run through they have to be closed (and the operator work a control to confirm it is clear of obstruction) well before it arrives. Hence the road closure times are a lot longer than with a half barrier which isn't so interlocked and just closes when the train approaches. Full barrier crossings therefore mean more inconvenience to road users. Recently NR has started installing crossings with radar and laser obstacle detection. In theory these remove the need for a human operator to supervise every cycle, though in practice they don't seem to be working too well yet, especially in snowy weather. For the obstacle detection to serve any useful purpose they must also be interlocked with the signals and therefore also have longer road closure times than automatic half barriers.

It's curious but statistics do seem to suggest that adding barriers is the most effective way to improve safety at an open crossing. Perhaps this means that some motorists have the mental equivalent of tunnel vision and ignore hazards unless they are directly in front? Or maybe they think that if the railway hasn't provided barriers it must mean that trains a very slow or very occasional and therefore it is worth taking the chance? At least with barriers a crossing violation requires a deliberate action to swerve round the barriers instead of just continuing along the normal carriageway. As I understand it these AOCL+B crossings effectively drive the barriers off the circuit that powers the lights, instead of total replacement of the existing circuitry to provide an extra circuit for the barriers, and therefore deliver almost* all the safety benefits of a barrier for much less cost than a traditional AHB conversion. *Some proving circuits are omitted.

Isn't Three Bridges going to take over part of the Great Northern as well? There are, in principle at least, three reasons why large operational control centres shouldn't affect reliability: (1) Losing an existing control centre, unless a very small one, probably cripples the service just as effectively as losing the whole of an operational control centre. There are a lot more older power boxes, electrical controls, etc, than there will be operational control centres so in that sense there is more to go wrong. (2) The cables coming out of the operational control centre will be carrying data streams to control and display large areas of the railway on a single cable. This means that if the proverbial bulldozer goes through them there is only a small number of cables to reinstate, and if they are properly planned there will also be duplicate cables that take a different route in which case there is no loss of communication at all. Doing the same just outside an existing powerbox means hundreds of cores of safety-vital cabling to be re-connected and re-tested. (3) Due to the use of standard hardware and digital communication as above, it is in principle possible to relocate an operational control centre to another site relatively quickly. I don't know what Network Rail's intentions are for this, and if I did I wouldn't post them here. This is of course rather theoretical and realising the potential benefits depends on good design and operational practice. For example there have recently been some power failures at large control centres which suggest that the duplicated or backup supply arrangements aren't all they ought to be. Also a lot of the more vulnerable existing equipment will remain in place for some time as a potential source of unreliability, just controlled from the new centre instead of the existing location.

No date on that photo as far as I can see, but some of the metal rings on the sleepers that the insulators sat on survived into the Metro era.

I think the presumption by some road users is that the train behaves like a road vehicle. They don't realise that it could be going a lot faster, it almost certainly can't stop, and it almost always comes off better in a collision.

Presumably the railway worked without major problems, starting whenever they first built it and continuing up until the spoil heap had been piled up alongside and started slipping. If the spoil heap is removed then there's no reason why the reinstated railway should have any problems.

They probably would be. Bus-only tunnels of any length are pretty unusual though, usually the passenger volumes that justify a tunnel would also justify a rail option, and the ventilation/fire/evacuation issues would be more difficult with a diesel bus. Not running through the city streets would also eliminate one of the main reasons why they chose bus in the first place...

As I see it they need to sort out this spoil heap one way or the other - they can't just leave it as a spreading blot on the landscape. Once they have done this there is no further risk to the railway so it can be relaid on the original alignment.

Didn't they take out the "sprung" points as part of the ERTMS work? If so then presumably the move suggested would have to be "signalled" and therefore may not possible with ERTMS out of use on the unit in question? Even if the points remain sprung, wouldn't this shunt involve a move into the section? If so authority would be required, which again would need would need a working ERTMS and wouldn't be granted if another train already had a conflicting movement authority.

Google has just found me a pic of the Prestonpans diversion mentioned above: Here's an aerial view of the result. About 1km of new alignment is needed to move the track laterally by only 100m or so (and the curves are continous so this wouldn't have reduced if the problem area had been the same width but shorter). This is probably a 125mph alignment and tighter curves for 75mph or so would most likely be acceptable at Hatfield, but it still gives some idea of the amount of work that would be needed. A non-starter in my view (though curves at Barnetby are even less likely).

No doubt the relevant authorities are looking into it. Of the Guinness variety perhaps - most disruptive railway geological incident since Penmanshiel?

I think realignment is out of the question. To move a line sideways by a few tens of metres involves moving it over a length of many hundreds, unless a severe speed restriction is acceptable over reverse curves. It would also require Transport and Works Act powers to go outside the existing railway boundary - a process which typically takes over a year although there may be a fast-track.

"and as to using expanding foam to make the embankments..."

Indeed it is. And on Jim's first pic isn't that piled retaining wall next to the loco leaning inwards rather ominously?

Taiwan high speed rail uses trains and other technology based on the Shinkansen, which according to the link is the first time it was exported. HS1 may have been the second!

It's understandable that a lot of people in the Chilterns are opposed to HS2, since they get the pain but none of the gain (not even better train service from released capacity as that will be on the WCML further east). Further north I think there is quite a widespread belief (rightly or wrongly) that HS2 will be a big benefit to their region, and that may reduce local opposition in some areas. Having said that I see the National Forest are expressing concern!

I recall one or two times in the 1978-81 period (when I travelled from Kirkcaldy to school in Edinburgh) that our 3-car 101 set was assisted by a class 20 on the front, but the DMU driver was driving as normal so there must have been at least one engine working. By then IIRC all DMUs in Scotland were 3-car sets with the possible exception of some exotic ones like the Aberdeen-Inverness sets.

Like the man said in relation to Dent (I may have the quote wrong, words to the effect of) "We put the station there so it was next to the railway".

I took a look at the route from Stalybridge up to Diggle recently. You'd need to put back about five large viaducts and build deviations (probably tunneling into the hillside) to avoid Greenfield and Uppermill where it has been built on, and even then the curvature means speeds and journey times would be little better than present. Once all the three and six car trains are up to nines or 12s then it may be worth thinking about a new Transpennine route (which could be Woodhead with a link northwards to access Wakefield and Leeds).