Edwin_m

I presume it is this one: extension://bfdogplmndidlpjfhoijckpakkdjkkil/pdf/viewer.html?file=https%3A%2F%2Fwww.railwaysarchive.co.uk%2Fdocuments%2FRAIB_Esher2005.pdf Signaller realised that if he put the signals back against a particular train as required by the rules, it would be more at risk of being struck by another one that had passed signal at danger due to poor adhesion. Another one here: Rail https://www.railwaysarchive.co.uk/docsummary.php?docID=4795 Driver did the right thing in reversing the train off an embankment that was being undermined by flooding, without consulting Control first. Two hazards here: a multiplicity of signal aspects close together can be difficult to discern from a distance, and if the individual signals have red aspects then the driver has pass a red signal, which is considered to degrade its importance in other situations (though it's allowed for subsidiary aspects and could be got round by only having one aspect, lit only when no proceed aspect was displayed). Problems of signal sighting may also be worse if multiple signal heads need to be easily viewable somewhere where space for them is limited.

This is the train length and signalling overlap problem I mentioned in my previous post. For those that don't know, and simplifying grossly, a train isn't allowed to approach a red signal unless the track is clear and the route locked for an "overlap" distance beyond the signal in case of any overrun. In this case the overlap for the further signals runs beyond the convergence of the two tracks, so if a train arriving in one platform is cleared to the further signal, no train can leave the other platform until sufficient time has elapsed that the arriving train must have stopped without running past the signal. It's possible to route a train up to the nearer signal to avoid this problem, but only if it's short enough to fit in that part of the platform.

The Ordsall Chord scheme (including Piccadilly and Oxford Road as you say) was an alternative to the Ardwick flyover, they were never both going to go ahead but it was concluded the Chord had a better benefit to cost ratio. There was never any 4-tracking between Piccadilly and Oxford Road - recognising that the occupation time of the station platforms was the limiting factor on route capacity, it was planned to provide two useable platform tracks in each direction at each station (Oxford Road has that already but they are too short and signalling overlaps mean that a train can't arrive in one while the previous one is departing from the other). The Chord was given the go-ahead on its own by the government in the early 2010s, and everyone professionally involved would have known it made little sense without the other enhancements. A Transport and Works Act order was submitted for Piccadilly and Oxford Road and just sat on the desk of then Transport Minister Grayling for years. This is what has just been withdrawn, pending some alternative option.

When a SI unit is spelt out in full it should not be capitalised, even if the abbreviation is upper case. My physics teacher said this was to avoid confusion with the name of the person it was named after, the unit sometimes being identical to the name as in watt/Watt. Never heard the thing about the space in 35 years of engineering. I run the number and unit together because unless you use some strange nonbreaking character in a word processor, it may decide to put a line break between them.

Hasn't the fairly recent re-signalling, mentioned in a previous post, removed one or both of these?

A typo in a set of minutes I saw a long time ago: "Fist line maintenance will be done by the local technicians".

How many stations still have more than one box, say within sight on the platforms? Off the top I can only think of Stockport and Shrewsbury.

Gizmo, probably not a towering intellect amongst cats, brought in two last week. Then last thing last night I saw him coming in with what proved to be fairly uninjured and fast moving one, which he proceeded to drop and it darted under the nearest furniture. Cue half an hour of tipping up various chairs and sofas in an unsuccessful attempt to locate it. This morning I found it under the sofa, scooped up an initially uninterested Gizmo and put him down in front of the sofa before lifting it again. I then put the cat, mouse in mouth, out of the back door and locked the cat flap. However, someone must have opened it again as half an hour later I heard the usual long miaow of triumph, and found Gizmo staring at an apparently living mouse that was cowering in a corner. I was able to pick the mouse up without suffering a paw swipe, and put it out of the front door without Gizmo following (the cat flap is at the back). Half an hour later it wasn't there, but I know not whether it had escaped to safety, Gizmo had worked his way round from the back and finished the job, or some other animal had swooped in. We have now bought a humane mouse trap to keep on hand in case one or more rodents is brought in and, unable to escape outside, goes on to live or die somewhere in the house.

Chester was re-signalled in the mid-1980s and the Leicester re-signalling a couple of years later eliminated the last semaphores between London and Sheffield.

The issue that may be significant here relates to acceleration not braking. One possible cause of such an overspeed is passing the signal at the normal speed for a diverging train, then accelerating so the junction itself is passed at a much higher speed than permitted. This is much more likely with a light engine or a modern high-powered EMU than with a traditional locomotive and coaches. There was indeed a re-evaluation of signalling when HSTs were introduced, which were the first to have the higher braking rate which is now universal for new passenger stock and mandatory for anything exceeding 100mph. One consequence was the introduction of flashing aspects, to replace approach control at certain junctions where the HST might be able to brake later to comply with the signals but end up too fast at the junction itself.

Indeed, though they will still have more acceleration. No such restriction if a driver of an 80x unit applies full power after passing a route indicator.

At the time of the Peterborough re-signalling, the usual train that might be accelerating after passing those signals would have been a Deltic plus 8. Occasionally that Deltic might have been running light, in which case I guess its acceleration on maximum power would be phenomenal (and there was a similar incident with a 90 at Bletchley a few years back). But these days most passenger trains approaching that signal are 80x units in electric mode, whose acceleration will leave the Deltic plus 8 in the dust.

As there doesn't look to be much room to widen the formation through St Neots, your suggestion implies extra trains on the ECML tracks, which would probably be unacceptable on this busy route. As it's Down-Down-Up-Up then it would also need a flyover each end, or flat junctions for an even greater capacity hit. According to discussions elsewhere, trains approaching from the north wouldn't be able to serve the new Cambridge South station, which is expected to be an important commuter destination, without more works further south to turn them back. There's also an aspiration for EWR trains to continue via Ely or Bury, which is more difficult if they have to reverse at Cambridge and pass over the junctions north of it twice.

I believe that in steam days the (G)WR preferred to change to its own locomotives on its own lines as both were fitted with the ATC system. I can't track down a date for the final removal of ATC but mid-1970s rings a bell (an AWS one!), so would this also have been a reason to change locomotives at places such as Bristol?

This Safety Advice is issued because their investigation so far suggests there is a significant risk of another incident at this location (unsurprising as there have been two already) which warrants a warning being put out. The investigation continues, and the final report may shed more light on whether it was failure to observe or failure to react, but for now they will deliberately have left this vague.

Trains that reversed at New Street probably had a loco change rather than a run-round - most were swapping to/from electric in any case. I think trains reversing at Gloucester (after closure of Eastgate) sometimes swapped too.

I seem to recall the original Euston electrification included a part of the NLL, presumably to allow freight trains to and from the docks to change locomotive.

I assume 90s would have been permitted to work into the dual-electrified platforms at Euston. Intercity push-pull formations were too long to go into these platforms but I think would have passed over short sections of the dual-electrified approach tracks.

In situations where there are multiple possible routes between two signals, there may be some means for the signaller to select one rather than another, such as an intermediate button or keying a point, or the non-preferred route being selected automatically if the preferred one is not available. But this will only be provided if there is some operational benefit, for example crossing over and back if another train is signalled over the piece of track that makes up the more obvious straight route between the crossovers. Getting back to the topic, how (if at all) does speed signalling protect against hazards such as an electric train being sent down a non-electrified line, or a train being routed towards a line where clearances or axle load aren't sufficient? In British practice the driver should be make aware this is going to happen in time to stop at the junction or at least beyond the junction but before any hazard can arise.

Never had any direct experience, but I'm often surprised by the reliance placed on a single locomotive or brake van to manage a heavy unbraked train on a descending gradient, which this would have become if a coupling had parted. I guess in mitigation, at that time of day and after a prolonged line blockage there was probably nothing in front to run into if that happened. But if a decent speed had been reached (how would the driver in front know a coupling had broken and braking was needed?), it's downhill all the way to the points that would be set for the low-speed move into the loop. I have visions of Crappys being sprinked liberally across the Bathampton area...

Unless the side of the coach was flat (which would reduce interior space), inward opening doors would have to be recessed, as seen on Pullman cars. This makes it very difficult for guards and platform staff to see an open door some distance away. I assume the Pullmans managed because of the number of on-train staff.

The FLIRT units supplied to Greater Anglia and Transport for Wales are versions of the same design complying with Network Rail structure gauge and other standards. Stadler specialise in small non-standard production runs so I imagine could produce a hydrogen version if wanted. The difficulty is probably more about working out how to operate and fuel it to provide an effective service and actually reduce CO2 significantly compared with a diesel version.

For a couple of years I shared an office and a railway telephone with one colleague. As we were both right-handed, whenever one of us turned the phone round to face us, we put another twist in the cable, which started fraying and pulling out of the back of the phone. Eventually we got a call from the operator asking if we'd called the 111 railway emergency number.

Early in the development of HS2 there was a report that considered several dozen sites in London before concluding that Euston was the best option - it may still be on the Web somewhere. So I think if there had been a better alternative they would have gone for it even if it altered the onward travel route of passengers who would travel via Euston today.

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.