Edwin_m

Resembling in name only the sort of bank activity that most of us come across, but traders in merchant banks need access to data within milliseconds in order to carry out transactions at exactly the right time to maximise their profits.  Time lags of 1 to 2 seconds are typical for railway signalling.  

I wasn't trying to suggest that railway signalling was particularly comparable to bank systems, rather the narrow point that card readers employ coding that ensures they can work securely over a communications channel that isn't in itself secure against tapping or other interference.  Potential fraudsters would have a big incentive to crack that coding, but as far as I know nobody ever has.  The vital communication between computer-based interlockings and the trackside employs similar principles to make it extremely difficult for anyone to hack into it even if they have access to the communications channel.  

Looks like the two side pieces would have to be placed at exactly the correct spacing and exactly vertical, otherwise the top piece won't fit.  

7 minutes ago, Michael Hodgson said:

Nonsense.  We've trained our four to come running when we rattle a tub of dreamies.

I'd say they can be trained if the incentive is significant and immediate, whereas dogs don't need that sort of motivation or at least not to the same degree.  Having said that Gizmo knows he shouldn't be in the kitchen and will leave if I point this out to him without me needing to shout (except when there's something good cooking).  He clearly knows what is expected of him but chooses to ignore it.  

On 26/05/2022 at 14:09, icn said:

At the risk of being OT: buildings have been moved for railway reasons in recent times, although the one I know of was moved in order to make space for additional platforms. (Obviously worth the money in that case, but not really worth the money if it's not in anyone's way.)

I don't think the new station site is chosen to avoid the old one - it's the logical place to put it particularly so the main entrance is alongside Moor Street and as close as possible to New Street without demolishing the Bullring or going underground.  If the old building had been in the way of this site then I guess they would have considered moving it, but I suspect we would have ended up with a station somewhere a bit less convenient instead.  

8 hours ago, 6892 Oakhill Grange said:

it seems to indicate that electrification to South Wigston will have been done by others before the main project is carried out.  I appreciate that we are in a detailed planning period post IRP and if wiring to Wigston had been approved, the government would have announced it 12 times by now, but does anyone know anything.

That would be consistent with the behaviour of governments over the past decade or two, but they seem to be taking a different line now.  Possibly some spin doctor has decided it's counter-productive to announce something that won't be completed for some years, or to announce it multiple times, or to announce something that isn't in the "north".  

Many places ban dogs but make an exception for guide dogs, which will be specially trained and can probably be relied on to behave.  Cats are well known to be untrainable.  

2 hours ago, corneliuslundie said:

A pity about the Curzon Street station as the early announcements I saw certainly suggested strongly that it was being incorporated as part of the new station. That is actually the end of the station where many people will want to enter and exit.

Jonathan

There will be an entrance to the station at that end, but the alignment means the old building is actually a short distance away from it, so it's difficult to see how it could have been incorporated as part of the operational station.  To do so would probably have required drastic changes in the historic structure in any case.  

The Sheffield-Rotherham tram-trains have the ability to run on 25kV as well as 750V, but it isn't used.  The overhead line on the Network Rail section is designed to be convertible to 25kV with minimum modification, although someone at NR later said it would have been better to provide standard 750V equipment and replace it if that section was ever energised at 25kV. 

I understand that there is a risk of damage if a system configured for 25kV is fed with 750V (too much voltage) or vice versa (too much current), so if the tram-trains lose power for more than a certain length of time a voltage detector circuit is employed to ensure closing of the circuit breakers to send the power to the correct set of traction equipment.  This requires a longer neutral section (measured in running time) than typical on a 25kV system.  I believe the old 25kV/6.25kV system did something similar, with spectacular results on a couple of occasions when it didn't.   

Lost track somewhat of where we got into this bit of discussion, but in an attempt to get back onto topic will point out that TfGM has been looking at ideas for tram-trains for at least 20 years, and these would require dual-voltage vehicles.  The tram-trains now being delivered for Cardiff Valleys will be 25kV or battery only.  

2 hours ago, Tony Teague said:

 

If tracks are in place they would presumably have come from the flyover end which certianly has track on it, indeed there are several trains per week scheduled to use a location called "Bletchley Summit of Flyover" e'g. tomorrow: https://www.realtimetrains.co.uk/search/detailed/gb-nr:BLTCSOF/2022-05-18/0000-2359?stp=WVS&show=all&order=wtt

Indeed so, but my point is about how the rails got from the end of the existing track to where they are needed.  For a normal renewal a rail train will drop rails at the trackside, and I believe this is done by anchoring one end of the rail and slowly drawing the train away so the rail comes off (I think it sits on rollers on the train).  But that can only be done if there is a track there already.  

3 hours ago, corneliuslundie said:

So how did Anonymous manage to hack the Russian public TV system?

And there are surely vital radio links in the system. Otherwise why all those masts on railway property (which can also get felled in storms)?

Sorry, not convinced.

Jonathan

My understanding is that they hacked the TV guides that appear on smart TVs to show their own message instead of the programme information.  These will almost certainly have a gateway to the internet so programme providers can log in and provide the details that are to be broadcast.  Such systems are able to be hacked, most likely by someone getting hold of the password. 

The are also not "vital" systems in the engineering sense - it's unlikely anyone will die if the TV programme fails.  Railway signalling systems are built to much higher integrity and separated from public access in the ways described by others.  They are also protected by interlockings which only respond to requested actions if safe to do so, so even if someone got access to the control system it would be extremely unlikely that they could cause a derailment or collision.  

I'm not familiar with the details for ETCS, but I know the SSI systems from the late 1980s employed digital coding of the data streams to ensure that controls and indications wouldn't be acted on if they were corrupted or, for example, the cable to the trackside was inadvertently connected to the wrong interlocking cabinet.  That's a much higher level of protection than the older relay interlockings, where most of the trackside cables just carry simple unencoded currents (although the short tail cables from the trackside modules to the actual equipment still do this).  It's similar in principle to the sort of coding that ensures that credit card transactions can be securely processed when the reader is only connected by non-secure wifi and landlines.  

9 hours ago, Davexoc said:

 

Passing Whaddon Road - Mursley today, I'm pretty sure there are rails out this far now, and heading towards Swanbourne. Possibly the eastbound line, which would be down, or is it up? I'm saying down because every way onto the line in that direction will be accessible from London.

Down is towards Bletchley.  This was previously Up, presumably because the line was originally built as a branch from Bletchley to Oxford so the LNWR's trains from London would use it in that direction.  So it's a rare example of Up and Down being reversed, which wouldn't have caused any of the usual problems because in most respects it's a totally new line.  

On the tracklaying question, how are the rails positioned with no tracks to bring them in on?  Does some suitable off-road vehicle have to drag a long string of rail along the ballast?     

You also need to be aware of the heat dissipation in the diodes or resistor, which is equal to the voltage dropped multiplied by the current passing through.  The power rating of the device needs to be greater than that figure, or it will burn out.  

On 06/05/2022 at 21:47, Nick Holliday said:

I recently got hold of a fascinating book on the Rosedale Mines and Railway, from the Scarborough Archaeological and Historical Society.  The line itself was built by the NER in 1871 to serve ironstone mining,  and was about fourteen miles long, mainly running along the top of a ridge in the Yorkshire Dales at over 1,000 feet, connected to the main network at Battersby by the Ingleby Incline, some 1,430 yards long, and, for most of its length, around 1 in 5 in gradient.  The line was worked at high level by various 0-6-0 tender locos, and a full shed and workshop was available at the end of the branch, at Bank Top.  The incline was so precipitous that the centre driving wheels had to be removed from locos when they were moved up or down the incline, and the works at Bank Top had shear legs to carry out this operation.

What I found interesting was an appendix that calculated the possible terminal velocity of wagons if the cable were to break as they started their downward journey. This was no finger in the air bit of inspired guesswork, but three pages of formulae that would have been at home in "The Big Bang Theory" and which, with a bit of computer assistance, came up with the impressive answer of 113 m.p.h.! There were plenty of runaways on the line, but I suspect none actually achieved this speed, meeting their ultimate fate before they reached it.

It would be interesting to see similar calculations for the various cable operated inclines in Britain, especially the ones in the Welsh slate quarries, but I don't suppose they were as long as Ingleby, but perhaps steeper.

That might depend on whether aerodynamic and other resistance forces have been considered.  I seem to recall Dionysius Lardner ignoring these and predicting an improbably high exit speed if a the brakes of a train were to fail in Box Tunnel.  I make the speed without resistance to be around 170mph, in a lot less than three pages, so I assume the calculation allowed for these resistances.  

Puts my own little faux pas into the shade - needing 10 battery holders for some kit I was building as a placement student in an electronics workshop, and ending up with 10 packs of 10.  I found an empty drawer in one of those metal cabinets those workshops always seemed to have, labelled it "battery holders", and for all I know they're probably still there 35 years later.  

It does look to be broader than standard string.  

Maybe it's the string they pulled when they needed to release the brakes when taking a GWR engine off and putting someone else's on?  

10 hours ago, jamie92208 said:

A ew years ago an embankment nearcWarrington was built with expanded polystyrene blocksvand is now carrying trains.

 

Jamie

So was the new embankment to the overpass at Nuneaton.  It is also used for platforms.  

2 hours ago, cctransuk said:

 

It's not largely true - it is THE truth, believe me!

 

As my career was spent in Cambridge, where the railway station is not within easy walking distance of the city centre - (a not uncommon situation) - I am acutely aware of the problem of accommodating public transport in city centres where it is not practicable to wholly exclude private and commercial motor traffic.

 

The example of Europe is invariably bandied about in these discussions - forgetting that much of urban Europe underwent an necessary total redesign post WWII, as a consequence of war damage. Fortunately, (or not, depending upon your perspective), this did not happen in the UK - with the notable exception of heavily targetted conurbations such as Plymouth and Coventry.

 

There are no obvious, easy solutions to the problems of urban congestion in the UK - but the enforced shift in energy use MAY be a spur to improving matters.

 

CJI.

Paris and Madrid are interesting in that context.  Both had major highway building in the later 20th century but retain a lot of older areas with narrow streets.  In recent years both have followed fairly aggressive anti-car policies.  

In a lot of cases it's the "inner suburbs" rather than the city centres that create the problem, as the roads aren't wide enough for bus priority and they are too far out for city centre traffic restrictions, that largely rely on places being in walking distance.  Cambridge (back on topic, sort of) has talked about various rapid transit schemes over the years, with varying degrees of practicality, but it probably needs tunneling to access the centre, which is difficult to justify in a fairly small city.  However that's more due to narrow streets and cycles than to cars.  

1 hour ago, cctransuk said:

 

Having been professionally involved in urban highway design for most of my forty year career, I can assure you that finding roadspace for bus priority in what are still basically Victorian road systems is nigh-on impossible.

 

CJI.

That's largely true, but less so if there is the political will to drastically curtail the use of cars and reassign the roadspace.  That's why I suggested that buses in more rural areas should connect with trains for the journey into the city.  In the case of EWR a bus interchange at Winslow could provide a service from Buckingham to Oxford for example.  But it probably wouldn't work without schedule and fares integration with the train, which is close to impossible in a deregulated framework.  

Indeed, buses could do a lot more for our public transport network if they had consistent integration (between themselves and with rail) and priority over other traffic.  This would allow a bus service to approach the quality and reliability of a train service, and would be entirely adequate for many missing transport links in areas where traffic congestion isn't an issue (possibly feeding into trains for the journey into the city where buses become unreliable).  Rail reopenings could then be much more targeted on where rail is genuinely the best option - for the avoidance of doubt and to get back on topic, I suggest that is the case for East West Rail.   

On 11/04/2022 at 15:17, Northmoor said:

It is the point always missed by those who keep going back over the same tried, tested and failed ground, to try to make rural and lightly-used branch lines viable by making the rolling stock lighter.

 

It is the cost of infrastructure and the staff that make railways a high volume business.  Just because your train weighs half as much, doesn't mean the driver costs you half the salary.

A train that can operate more like a tram might be useful in this context, by allowing steeper gradients and tighter curves and even a limited degree of street running where necessary.  This might make it easier to re-open a route where some sections have been built over.  However, per seat, trams are more expensive than trains so this isn't necessarily a low-cost solution.  

These days it's probably relatively easy to get agreement to a station on a gradient provided it's not somewhere trains reverse - if the driver is in the cab then they should be able to stop any runaway.  On modern multiple units parking brakes are applied automatically, so it's very unlikely they would be left unbraked due to driver forgetting to apply the parking brake and unit running out of air.  

6 hours ago, DY444 said:

 

The problem with TPWS is that there have been a number of collisions in recent years that it didn't prevent.  Salisbury obviously because it can't do anything about brake failures or locked up sliding wheels, and the rest because the protecting signal was cleared for a permissive movement. 

 

You can provide all the train protection you want but permissive working or degraded working under failure are always going to present a higher risk.  If you allow light weight vehicles with low crash worthiness to mix with "ordinary" trains then sooner or later the Swiss cheese holes are going to line up and the two are going to come together.  We know which one will come off worse.

That's fully understood, but you can't protect against all collisions and even with trains meeting the full crashworthiness standard the consequences of collisions can be severe.  It's one of the few areas where the safety authorities have accepted a principle based on balance of risk rather than on absolutes.  

27 minutes ago, Andy Kirkham said:

Regrettably decided not to go. The journey by public tranport from Bristol entails two changes of bus with the final leg rather infrequent. Any cancellation due to Covid would wreck the schedule. Don't want to risk getting stranded overnight in Shepton Mallet.

I could have arranged to be staying in the region but without a car, and I also found that bus services were somewhere between impractical and nonexistent.  I was under the misapprehension that the Bath and West Showground was actually somewhere near Bath!