What is this track cabling and yellow box? (Photo)

[trebor79]

Another downside is that traincrew can't use track circuit clips to protect the adjacent line in the even of an accident such as derailing foul of it. The Stoke re-signalling, one of the first to use axle counters widely, had phones every few hundred metres in the cess as an alternative means of stopping trains in emergency. But I guess the advent of universal GSM-R with the emergency stop button is now considered enough to make that unnecessary, as it should stop other trains far more quickly than getting down to the track and applying a clip.

This came up first on the Euston job two years earlier, with the installation of axle counters through Primrose Hill Tunnel and a little way towards Kensal Green.

I’m wondering, though, when the last time a track circuit clip was used in an accident.

I guess these days the driver or guard just presses the appropriate button on the GSM-R panel and that will send a stop signal to all trains in the area?

 

[Dieseldriver]

I guess these days the driver or guard just presses the appropriate button on the GSM-R panel and that will send a stop signal to all trains in the area?

If the GSMR is functional. If you’re unable to get immediate contact with the Signaller and get confirmation of signal protection then it’s the full emergency emergency protection with TC clips and dets.

 

[alxndr]

Isn’t there a country that has to have an operational restriction of no more than (something like) 256 axles per train due to design limitations of the axle counter system? (Vague recollection from a Matt Parker live show)

Switzerland. It's also in his book, Humble Pi.

https://twitter.com/standupmaths/status/1185544321933758467?s=20

Trains in Switzerland are not allowed to have 256 axles. This may be a great obscure fact, but it is not an example of European regulations gone mad. To keep track of where all the trains are on the Swiss rail network, there are detectors positioned around the rails. They are simple detectors which are activated when a wheel goes over a rail, and they count how many wheels there are to provide some basic information about the train which has just passed. Unfortunately, they keep track of the number of wheels using an 8-digit binary number, and when that number reaches 11111111 it rolls over to 00000000. Any trains which bring the count back to exactly zero move around undetected, as phantom trains.

I looked up a recent copy of the Swiss train regulations document and the rule about 256 axles is in there between regulatiosn about the loads on trains and the ways in which the conductors are able to communicate with drivers.

== Doublepost prevention - post automatically merged: 5 May 2021 ==

Although this is an advert it does illustrate how the Frauscher wheel sensor and axle counter system works. It has a number of advantages over other systems including ease of installation (and temporary removal while tamping is going on), no electronics trackside, simpler serial interface to some types of computer based interlockings (using the WESTRACE protocol), doesn’t count spokes on some types of wheels (Steam loco’s!), and significantly cheaper, etc. etc.. Frauscher is an Austrian Company.

I'm not a fan of these, I find them (personally) fiddlier to set up, and I find something which is firmly bolted through the rail far more secure, although I think they have tweaked them a bit since they were first introduced and that's now less of a problem than it was.

 

[edwin_m]

Switzerland. It's also in his book, Humble Pi.

https://twitter.com/standupmaths/status/1185544321933758467?s=20

== Doublepost prevention - post automatically merged: 5 May 2021 ==


I'm not a fan of these, I find them (personally) fiddlier to set up, and I find something which is firmly bolted through the rail far more secure, although I think they have tweaked them a bit since they were first introduced and that's now less of a problem than it was.

If this is true it could have rare but catastrophic consequences. For example what if a train goes into a section to assist another, and the two have 256 axles in total, or one with more than 256 axles comes to a halt standing on the counter? I hope it's been fixed on current designs.

 

[MarkyT]

If this is true it could have rare but catastrophic consequences. For example what if a train goes into a section to assist another, and the two have 256 axles in total, or one with more than 256 axles comes to a halt standing on the counter? I hope it's been fixed on current designs.

I imagine it's a problem with first gen electronic axle counters, which Switzerland may have been an early adopter of, like neighbouring Germany. It's highly likely that new and fully modernised routes such as the Gotthard base tunnel will have the more modern versions that could handle the longer trains plausible on such gently graded freight trunks. For a longer train to run however, it's entire route would have to be free of such a restriction.

 

[2192]

How often do you need a train with anywhere near 256 axles? The limit would be a Bo-Bo pulling 63 bogie coaches/wagons; or a Bo-Bo pulling 31 wagons and pushing a similar disabled train to the next loop.

 

[trebor79]

How often do you need a train with anywhere near 256 axles? The limit would be a Bo-Bo pulling 63 bogie coaches/wagons; or a Bo-Bo pulling 31 wagons and pushing a similar disabled train to the next loop.

Those sort of train lengths are quite common in America and Australia, off the top of my head.

 

[Annetts key]

The older axle counter system (from 1988) that we used to have could handle axle counts up to 511 axles.

 

[alxndr]

The older axle counter system (from 1988) that we used to have could handle axle counts up to 511 axles.

Looks as though that's due to the same root problem as the Switzerland 256 problem, except using a 9-bit system instead (111111111 in binary is 511 in decimal).

 

[MarkyT]

The older axle counter system (from 1988) that we used to have could handle axle counts up to 511 axles.

I think they were already being used routinely in Germany during the 1960s & 70s, so quite likely Switzerland as well. When I joined the BR(W) drawing office in the early 1980s, the first batch of schemes with axle counters were being planned. Early jobs were Severn Tunnel, West Wales, Abercynon branch reopening to passengers (also an early SSI project). Some minor schemes in Cornwall also had axle counters. Around 1990 the Dawlish sea wall was retrofitted with axle counters after the brand new jointless track circuits provided under Exeter resignalling proved extremely unreliable (note before that there was only very limited track circuiting in this Absolute Block area)

 

[Annetts key]

Looks as though that's due to the same root problem as the Switzerland 256 problem, except using a 9-bit system instead (111111111 in binary is 511 in decimal).

Yes, all digital systems have such limitations. Just like the limited number of IPv4 addresses due to the use of a 32-bit number.

But as far as I know, the BR network did not have any restrictions on the number of axles in a train formation, as the powers that be considered that there would never be a train on the network with 512 axles.

It was fun when a train ran using the reversible signalling, then as it entered the axle counter section the count would go from 0 to 511, then 510, 509, 508 and continue counting down etc..

Of course, if you use ten binary bits, then the maximum count approximately doubles to 1023. And if you use 16 bits, it’s then 65535 axles which is I think what modern system use.