Edwin_m

50 minutes ago, Michael Hodgson said:

Slotting is a method in semaphore signalling whereby two signal boxes exercise control of a signal arm, that is both boxes have to pull their relevant lever in order to clear the signal.

And these days is used more widely for a situation where two signal boxes have to operate controls to clear the same signal, including for colour-lights and relay or computer interlockings where there is no physical slotting mechanism involved.  

52 minutes ago, adb968008 said:

But even fewer will use it as it is no better than the solution via Euston today.

From places served by HS2, I'd say it would be the preferred route to get to Heathrow.  As well as the journey time saving to Old Oak, there will be one relatively simple change of train there instead of the schlep from Euston to Paddington or the Piccadilly.  

10 hours ago, Ron Ron Ron said:

 

....and this decision to delay, will cost very dearly indeed.

 

The Euston tunnels TBM's will have to delivered and start tunnelling, at least as far as a few hundred metres, beyond the Atlas logistics tunnel.

Otherwise, once the OOC HS2 station construction passes a certain point, there'll be no way of getting them below ground, assembled and prepared to start tunnelling.

The only way to get the sections in, is via the Victoria Road access, or the OOC station box..

And presumably then they then sit for a couple of years doing nothing, in a confined and possibly damp environment.  And are expected to work perfectly thereafter, without any possibility of pulling them out for maintenance.  

17 minutes ago, Peter Eaton said:

Per last message :-

Believe when the ''Channel Tunnel'' was being bored water came in though their test bores under the channel

One to remember ! or in this case not learned from history.

I saw a TV programme recently (probably a repeat from some years ago where they interviewed a geologist who was called out to one such leak.  She tasted it and was able to reassure the workforce that it was a fresh water spring and not an inundation of the sea.  

15 hours ago, wagonbasher said:

All mammals and birds have four limbs, what evolution does with them is varied and sometimes bizarre but, Centaurs, Pegasus, Griffons and dragons all have two too many limbs.  

Gizmo has at least eight when we're trying to get him into a cat box.  

18 hours ago, Morello Cherry said:

Just a thought back to whether the whole or part of the station is electrified what happened in the Southern Railway London termini? For example was all of Waterloo electrified before the Portsmouth line electrification or just the platforms that the suburban electrics used? Likewise was all of Victoria electrified in one go or just parts of the station?

 

Part of the reason I ask is I came across this photo of Pirbright with just the slow lines electrified.

 

 

A more recent example is between Kings Norton and Longbridge, where only the outer two tracks are electrified (25kV in this case).  Continuing on towards Barnt Green only the inner two are electrified.  

Most tram-trains can pick up either their main line voltage (15kV or 25kV) or 750V from the same pantograph, including the Sheffield ones although those only every use 750V.  Changeover is via a longer than usual neutral section which causes both sets of traction equipment to be disconnected until a voltage sensor works out what the new voltage is and connects the appropriate one.  I believe this is similar to the old 6.25kV to 25kV changeovers in places like Glasgow, and also carried some risk of a large bang if something goes wrong!  

9 hours ago, The Pilotman said:

Thanks for providing that extra detail. Based on what you’ve written, it does sound like some sort of issue with the signalling equipment somewhere. Perhaps something was being worked on at the time and the signalman was trying to cover for an error that he knew someone else had made (that certainly used to happen). Whilst I’ve never heard of an incident quite like this (a signal aspect completely at odds with the actual route set), extremely unlikely events can occur as the Clapham Junction crash demonstrated. 

Some similarities to this derailment, probably caused by technicians doing the wrong thing, though inside the equipment room in this case.  The chain of events is consistent with someone working on the circuits and managing to reverse the points after the train put the signal signal back to red but before it reached them.  Depending on circuit design and the exact error made, the route lights could be wrong and the point out of correspondence on the panel, but the former could be explained if the signaller put the route back as soon as the train passed, and the latter if whatever fault was cleared before anyone noticed.  

https://www.railwaysarchive.co.uk/docsummary.php?docID=529

8 hours ago, melmerby said:

Another good episode tonight.

 

The bit about the Lincoln railway history missed out a particularly awkward level crossing at Pelham Street (Durham Ox Jn.), east of the station where the GCR crossed the GNR on the level (to get to the MR station) in the middle of the level crossing:

Note the signalling wires/rods coming over the bridge from the signal box

 

Eliminated when the elevated road was built in 1961

 

NLS georeferenced map:

https://maps.nls.uk/geo/explore/#zoom=17.1&lat=53.22528&lon=-0.53571&layers=168&b=1

 

 

It was an interesting and unique bit of railway, but these days all there is to see is a junction underneath a 1960s flyover, so it probably doesn't make very good television.  

19 hours ago, 45655 said:

Presumably the fourth rail is bonded to the running rails on this section (and there is a train length dead section for tube stock at the transition) as the DC lines stock is third rail only.

The gap only needs to be one coach long.  Main line units have a bus cable linking the shoes within the unit, but tube stock only links the shoes on an individual car.  

For long freight trains in North America, a brake release and recharge can take several minutes.  This is why separate locomotive brakes (generally dynamic, regenerating via the traction motors and dissipating heat in resistors) are so important for keeping the train under control when descending long gradients.  

10 hours ago, woodenhead said:

This:

 

The guy that was objecting to the planned path wanted a bigger curve through the middle of that land in the middle, the court case was to preserve the chosen route and as soon as they won they got on with building as well as demolishing stuff near the museum.  Basically a whole regeneration project depended on the chosen route to maximise the land for development.  Whilst the curve itself did not start the development I reckon it unlocked the land once NR finalised the route as until it was chosen the area was blighted by a planning proposal for a railway.

Thanks for clarification - I vaguely remember it now.  However, all it needed to unlock the land was a decision that the wider curve would never be built, rather than a decision to go ahead and build what they actually did.  I agree that without the work at Oxford Road and Piccadilly, this curve (now carrying only one train per hour) was a monumental waste of money and an indictment of the way politicians (don't) plan and fund rail projects.  

2 hours ago, CWJ said:

 

I don't normally use fiery language like that but I as a Northerner I felt confident in assuming that the good folk of Northern England and the Midlands would find it useful to be able to catch a direct HS train to Heathrow rather than having to change trains, drive or take a connecting flight from a Northern airport. It would certainly appeal to me as it would be quicker than all the other options if you take into account the delights of parking your car or enjoying the various queues at two airports.

This has probably been done to death a few dozen times on the HS2 thread.  But in short, about 8% of the passengers on HS2 were predicted to be going to Heathrow so it would be difficult to provide a good service there without inconveniencing the much larger number heading for central London.  Even if they did that, you'd still not be able to serve all terminals directly.  Old Oak Common has a frequent service to all terminals.  

3 hours ago, woodenhead said:

The cynic would say because the chord released land for building development i.e. cash whereas any work on the Castlefield corridor would only cost money and reduce development potential.

What land was released please?  

9 hours ago, woodenhead said:

How the world changes:

 

BR: "Lets divert the Trans Pennine services via Oxford Rd and Piccadilly, rebuild Victoria with a smaller footprint and pocket some cash"

NR pre 2016: "Lets send more Trans Pennine trains via Victoria, throw in a curve so they can still access Piccadilly and then onwards to the airport"

NR post 2016: "We've built the curve but we've lost the funds to develop the Oxford Rd corridor, so lets just go back to Victoria being the prime station for Trans Pennine services that don't go to the airport and we won't talk about the curve.

NPR: Let's make Piccadilly the prime station, so we can use parts of HS2 to continue to Liverpool.  

38 minutes ago, jjb1970 said:

On maglev, I'm not sure the fact it is incompatible with existing trains is such a big issue. The Japanese Shinkansen lines were built as dedicated lines to a different gauge from the existing JR network (though contrary to popular belief, there are were already standard gauge railways in Japan and a few of the non-JR railways are standard gauge), ditto the new high speed railway in Indonesia and the planned Thai high speed line and no doubt others. 

It's probably OK if there is a plan and political commitment to build a comprehensive network in a reasonable timescale.  Clearly we don't have that in the UK, and if HS2 had been incompatible with the classic network then passengers from the North West to London would be forced to change at Birmingham (and possibly again at OOC) for many years.  

1 hour ago, J. S. Bach said:

An equal number of cats and traps always looked good in the pilot's logbook!

So I guess carriers don't have a mouse problem...

Contractors and consultants also have to spend a lot of money putting their bid together, which involves some very detailed planning if they are to reduce the risk of underbidding and losing money.  There's always a clause somewhere which says the employer reserves the right to cancel the tender process and the bidder can't then seek any recompense (quite apart from the money being lost if someone else wins).  If the government gets into the habit of issuing tenders and then doesn't proceed with the work, the next time they may find that suppliers bid high to allow for the risk premium or just don't bid at all.  

1 hour ago, melmerby said:

What was going on with that clock at Findlaters Corner?

It was said that it had been sent away to a clock restorers in S. London.

What we saw going back, appeared to be a mostly new dial and a radio controlled electric mechanism. I doubt that was what was removed.

I guess the face and the hands could have been original.  The mechanism, not so much.  

Seeing the ROC at Ashford not in use might only have been a tempory control from France.  Presumably they need to use it from time to time to keep the staff current.  They may even have scheduled a swap so Tim's visit could be confined to British territory.  

Interesting that the re-used section of 1974 tunnel only appeared to be a few tens of metres long, although I think there was another set of cast iron segments visible in the distance at one point.  If that's all there is then I'd have thought it would have been easier to just get rid of it rather than trying to re-use.  

The reasoning for a station at OOC most likely goes back to the original idea of connecting to Heathrow, and I think was entwined with the decision to turn down the third runway and provide better rail connections instead of more domestic flights.  A branch there would have been very difficult and expensive, and would only have served one or two terminals directly so many passengers would have needed to change again.  IIRC only about 8% of passengers were expected to head there anyway and it was quite hard to develop a service pattern that provided for them without inconveniencing everyone else.  Early designs included provision for a future junction towards Heathrow, just south of the Chiltern tunnels I think, but it was deleted.  A stop at OOC allows passengers access to any terminal at Heathrow without a further change of train.  

Part of the difference in China may be that they have more engineers in positions of political power.  

2 hours ago, Ravenser said:

BBC references to possible effects on some of the design teams for Euston hints there might be thoughts of doing the new high speed station at Euston in two phases - say 6 platforms for 2035 , and expanding to the full 10 platforms by 2041-3 .

Part of the claimed benefit of downsizing Euston HS2 from 11 to 10 platforms was the saving of time and cost, because it allowed the station to be built in one phase instead of two...

Anyway, as mentioned, construction is well under way and the parts of the existing station within the footprint of the 10 platforms have already been demolished.  

4 hours ago, Bernard Lamb said:

Back in the day they are alleged to have included deliberate mistakes rather than errors.

Two reasons.

1/ To easily show that an illegal copy has been made. 

2/ They were as the name suggests military maps and it is not a good idea to be too accurate in case the wrong people get hold of them. I have always taken the details of railway tracks with a large pinch of salt for that very reason.

Bernard

We now know that the Russians had far better maps of UK military sites than the British public was allowed to have.  

Quote

 

The GW and LNW jointly owned the Birkenhead Railway. As part of that arrangement the GW had running rights into Manchester from Chester. The GW wanted those rights to be to London Road but the LNW didn't want more traffic over the elevated section of the MSJ&AR in Central Manchester so they agreed that the rights would run to Exchange instead. GW locos were serviced at Ordsall Lane and GW trains to Manchester were withdrawn in 1941.

The GW did have an office in Manchester but I can't remember where it was. 

 

The line from Chester to Warrington was genuinely a joint operation as part of the Birkenhead Railway.  The GWR had its own warehouse at Liverpool Road, now part of the Museum of Science and Industry. 

https://www.pressreader.com/uk/heritage-railway/20210416/282342567660431