Edwin_m

The flying arches are listed and also unique. There are several surviving NER footbridges. If this one was kept it would have to be raised on a plinth, high enough to maximise the distance between the wire and the platforms, which would completely spoil the looks. Best option would be to donate it to some deserving preserved railway.

Some work beyond site clearance is in progress at both sites, although neither has much that is recognisable as a station. For example, at OOC the box is being excavated and at Euston new Underground ventilation passages are being dug to allow demolition of the former station on the west side where the ventilation now is or was.

Don't put it in the wheelie bin or it will probably melt it!

It's still considered to be significant by the people who claim to understand such things. It's actually cited as a reason to bring the cities of the North closer together by building a new railway between them to reduce travel times, so that they have the same sort of "critical mass" as London. Not that that means anyone will be going from Manchester to Leeds to get a bucket of greasy chicken.

An example of "agglomeration effect"*, rather like people might go to Hatton Garden to shop for jewellery? If people know they go to a certain place for piri-piri, then find their preferred outlet is closed or has a queue, or the other one just looks nicer, then maybe they'll try that one instead? *This may or may not be a comment on their sauce.

They're certainly self-acting, though I think the mechanism is more complicated than a simple spring. I seem to recall the original version had to be replaced because parts were no longer available.

Some areas with bi-directional signalling are fitted with "Patrollers Lock-Out Devices" or PLODs, which inhibit the setting of any "wrong direction" route while someone is patrolling the line. Patrollers normally have (or had, largely extinct these days) to walk in the four-foot to be able to carry out their inspections.

That's not what I was taught on track safety courses from the late 1980s until mid-1990s and as far as I'm aware it's the same today. It surprised me too at the time, but the logic is that from the four-foot it's relatively easy to get to the cess, a place of relative safety with only the one rail to cross. From the six-foot you have to cross two rails, and if two trains approach simultaneously you don't know which way to go. Lying down in the six-foot was indeed the recommended advice if trapped in that situation. If you're on the track when a train approaches then the four-foot is no doubt more dangerous than the six-foot, but the six-foot is the most dangerous place to do any on-track work. Just done an image search for voidmeter, and none of them look like the one in the OP.

Perhaps because the four-foot is safer than the six-foot?

It appears to coincide with a fishplate, ballast has possibly been added to the sleeper bays each side but the one in question appears to have less ballast. I wonder if it's some kind of jack to support a dipped joint.

Trap points have to be restored to their normal (trapping) position at all times except when a legitimate move is signalled. On mechanical signalling I assume this is just done by instruction, but in power signal installations they either have a flashing reminder on the panel, or they auto-normalise unless specifically keyed into the reverse position.

Even if wagons are secured with handbrakes, it's been known for them not to be sufficiently applied or for vandals to release them. In those situations the trap point is the last line of defence.

Indeed. If it was built for 125mph you might reduce the track spacing and clearances a bit, and simplify the overhead line and power supply a bit, neither of which is very significant in relation to the total project cost. The main difference may be tunnel cross-sections, but several of the longer tunnels won't be cleared for maximum speed anyway. The London-Birmingham route is largely able to achieve a good alignment, although gradient restricts speed through the Chilterns. Further north, mainly on sections now dropped from the scheme, there were parts of the route where lower speeds were accepted to curve round obstacles, rather than introduce extra tunneling under settlement or through hills.

A short between the pickups and the motor connections (perhaps better described as an unwanted connection, as it doesn't actually cause a short circuit) wouldn't affect operation on DC - it's just another way of getting the current from the pickups to the motor. But when a decoder is used, that short will be applying track power to the decoder components that are intended to drive the motor, and this will almost certainly destroy them.

Many post-privatisation EMUs have provision to be converted between 750V third rail and 25kV overhead, but unless I've really missed something no British DMU design is easily convertable to electric. Even the Voyagers, which have electric transmission, were found to be difficult when it was proposed a few years back to add an extra coach with a pantograph and transformer. There would have been problems with the new cables feeding the power through the train to the motors.

It definitely should be, but I'm not convinced it actually is - certainly in the UK? Can you offer any examples? The CAF class 331 EMU and 195 DMU are visually almost identical, but the 195 uses mechanical transmission so isn't easily convertible to a 331 - probably no provision for a pantograph or transformer either.

With electrification plans being scaled back, we are likely to see more DMUs ordered. These are likely to have hybrid drive, convertability to future electric/battery/hydrogen, or the maximum commonality of components with EMUs. This most likely points to electric transmission, helped by the availability of mass-market components from the automotive market (just as happened with mechanical transmission for the first-generation DMUs).

That illustrates how HS2 will only be successful if stations are "fed" by other public transport links, so as many people as possible can leave the car at home or not need one in the first place. By serving city centres near the existing stations, it can take advantage of the existing feeder services (not that they are always very good!), but public transport in rural areas is always going to be much more sparse. That's why HS2 also provides park-and-ride near Birmingham and Manchester, so someone can park there and get to the centre of another city where a lot of people have their destinations. But most journeys from one rural location to another one are probably always going to be easier by car, because someone trying to use public transport will probably need a car to reach their final destination.

Looking at the photos, I think they are building some hefty cross-members as they go, though I may not be fully understanding what is being shown. Typically this sort of structure will have these, which hold the sides apart during construction and afterwards, and can also support the floor(s) above track level. There is another form of "top down" construction that still involves building the bottom first, though probably not used much these days. Thinks of the caissons used to build things like the piers for the big Victorian railway bridges, where more height was added to the top and the combination of the extra weight and workers digging out at the bottom caused it to sink into the ground.

Wouldn't he then be called Banana?

Did it have to shunt to make way for a faster train?

I think the reason is that the arch of the tunnel has to be circular (or nearly so) to hold up the earth above it, and usually the curve continues down to trackbed level. One or two tracks fit quite well into a bit more than a semi-circle, but with three or more the crown of the tunnel would be a long way above the top of the trains, so a lot of earth would be dug out unnecessarily. Therefore, as you say, anything more than two tracks will generally be a combination of single and double track bores. There are a few exceptions, but I would hazard a guess that these are cut and cover tunnels, where the earth above the track has to be dug out anyway as part of the construction. The Marsh Lane tunnel posted above looks like an example of this.

Looking at the space available, I think a connection to York Road for a decent length of train would have made it impossible to use the easternmost of the tracks through Gasworks Tunnel for anything else. In any case, the connection for return services on the other side of the station has now disappeared underneath the newish station building extension. These curves were always heavily restricted due to clearance, so probably couldn't have taken even the few classes that are cleared for the Thameslink core.

There would also have been the flexibility for a train from London to depart from Derby in either direction. Without having any particular knowledge of the subject, I'd guess that the milk tanks would have been better on the rear, so they could be taken off by another engine at St Pancras and moved quickly to wherever they were unloaded.

Smithfield Sidings, but they are only long enough for an 8-car unit. I seem to recall the reason for the overlap of systems between City Thameslink and Farringdon was so the train would attempt to change systems at the first of those stations, but if that failed it could continue to the other one, and reverse out via the crossovers in between.