Buffer stop lights

[ASharpe]

Someone didn't at Enfield Town

Careful on discussing that here, I think it is still before the courts.

 

[ComUtoR]

Certainly should do, surely.

You should set the DRA when leaving the cab; which would generally cover the buffers, but isn't specifically mentioned. However, I have spoken with other TOC Drivers and they don't set the DRA at buffers.

 

[bengley]

Do you set the DRA at a buffer ? If it doesn't have a red light on it do you still set it ?

Cheers in advance.

Yes but that's not because there is a red signal ahead, that's because I'm immobilising the cab and leaving it.

 

[12LDA28C]

However, I have spoken with other TOC Drivers and they don't set the DRA at buffers.

That seems bizarre, bearing in mind that the driver is clearly going to leave the cab to either change ends, or leave the train altogether. So the next driver who accesses the cab will find the DRA not set.

 

[jupiter]

You need to put the DRA on because you’re changing ends.

 

[ComUtoR]

. So the next driver who accesses the cab will find the DRA not set.

I believe the theory behind it is that the new Driver sets the DRA to remind them of the signal.

I always found it odd but accepted it as some buffers don't have reds or are even lit. Always interesting to see the differences across our grade.

 

[alxndr]

Are the associated TPWS grids connected to the signaling system, or are they, too, just permament fixtures set to a single state?

Connected to the signaling system.

 

[skyhigh]

Do you set the DRA at a buffer ? If it doesn't have a red light on it do you still set it ?

Cheers in advance.

I set the DRA at a buffer simply because there will be no further movement from that end and it's part of my process for securing the cab.

I believe the theory behind it is that the new Driver sets the DRA to remind them of the signal.

Interesting as our TOC is the opposite. You are required to set the DRA when leaving a cab (and on entering, if you discover it is not set). You have to then check the signal before you turn the DRA off.

I've been stopped and cautioned once for a buffer stop which had its red light out. To be honest I think it's a bit stupid and unnecessary. Drivers know where the stops are.

To be quite honest it never crossed my mind to consider reporting it to the signaller. Maybe next time I'm bored and arrive into platform 1 I'll report it and see how the signaller reacts...

 

[Annetts key]

In my area, buffer stop lights were not originally provided. Henceforth, when provided, they are all supplied by and maintained by M&EE/D&P/E&P. And as far as I know, they all are fed from a 230V (240V) AC mains supply. Although I don’t know if the supplies are derived from station supplies or point heating supplies or somewhere else.

Are the associated TPWS grids connected to the signaling system, or are they, too, just permament fixtures set to a single state?

All buffer stop TPWS installations are part of the signalling system. Normally they will be energised continuously. These systems are also normally proved, but how this is done may vary.

 

[ComUtoR]

Normally they will be energised continuously. These systems are also normally proved, but how this is done may vary.

When would a buffer stop TPWS not be energised ? I thought they were standard OSS set to "10" mph

Cheers in advance.


*OSS - Over Speed Sensor

 

[zwk500]

When would a buffer stop TPWS not be energised ? I thought they were standard OSS set to "10" mph

Cheers in advance.


*OSS - Over Speed Sensor

If there was a failure? In which case an alarm that the OSS was no longer protecting the stops would be quite a handy thing for signallers and drivers to be made aware of.

 

[ComUtoR]

If there was a failure?

Totally understand that but @Annetts key said 'normally' and @alxndr says they are connected to the 'signalling system' so I'm kinda curious if there are different kinds of TPWS installations at buffers or indeed if there are various and odd exceptions to what I understand as being the norm.

If there was a TPWS failure; buffers or otherwise, would there be an alarm ? As a Driver I wouldn't know if TPWS was working or not unless I had a spurious activation (which does happen)

 

[Annetts key]

When would a buffer stop TPWS not be energised ?

TPWS systems are classed as safety systems, but are not classed as fail safe systems. So there is always the possibility that a system may fail.

The standard design is to arrange for the proving system to be included in the interlocking requirements of any signal reading up to the buffer stops. However, how and if this is indicated to the signaller varies.

Off topic, but TPWS installations associated with controlled signals will extinguish the signallers red indication for that signal. On modern signalling systems there will often be a separate TPWS indication.

 

[ComUtoR]

The standard design is to arrange for the proving system to be included in the interlocking requirements of any signal reading up to the buffer stops. However, how and if this is indicated to the signal varies.

Does this mean that a signal sending you into a terminal platform/Buffer would potentially have two TPWS grids associated with it ? (one before the Signal and the one for the buffers)

 

[alxndr]

Totally understand that but @Annetts key said 'normally' and @alxndr says they are connected to the 'signalling system' so I'm kinda curious if there are different kinds of TPWS installations at buffers or indeed if there are various and odd exceptions to what I understand as being the norm.

I was just being lazy in the amount of detail I went into as we are veering off the point of the original post somewhat, although with anything signalling there's almost always an exception somewhere (although I don't know where in this case) so probably shouldn't have been so broad.

If there was a TPWS failure; buffers or otherwise, would there be an alarm ? As a Driver I wouldn't know if TPWS was working or not unless I had a spurious activation (which does happen)

To the signaller, yes. Depending on the age of the installation it might appear as the same as a lamp out when the signal is at danger, or might be its own indication. In older installations it was deemed too intrusive/risky to add additional indications to the panel so the TPWS proving was cut into the lamp proving circuits.

There will also be an indication on the module controlling the TPWS to show that it's failed at some point since it was last reset to aid fault finding by hopefully narrowing down whether it's the OSS or TSS that's having issues, but isn't repeated to anyone other than the technician attending.

Does this mean that a signal sending you into a terminal platform/Buffer would potentially have two TPWS grids associated with it ? (one before the Signal and the one for the buffers)

Usually the one for the buffers will be associated with the buffers and not the signal.

 

[Annetts key]

Does this mean that a signal sending you into a terminal platform/Buffer would potentially have two TPWS grids associated with it ? (one before the Signal and the one for the buffers)

Yes. It’s possible that there could actually be more.

TPWS grids are always used in pairs. The first one in the direction of travel is called the ‘arming’ ‘loop’ and the second one is called the ‘trigger’ ‘loop’.

For a main line controlled signal where this is a point of conflict (such as a junction) ahead of it, it will always have a train stop system (TSS) TPWS. Depending on track layout and line speed, it may have an Over Speed System (OSS) TPWS. All these are on the approach side of the signal.

Then after the signal, on the approach to the buffer stop, there will be another ‘buffer stop’ TPWS system.

 

[Chris Hamilton]

I've never maintained one, although I can't say that there won't be somewhere in the country where they fall under S&T. I know for certain that the white light above the buffer stops at the end of the turnback sidings at Bedwyn are 240V and therefore fall under the remit of the Distribution and Plant department.

I’ve got Edinburgh Waverley in my remit, which as you can imagine has a lot of buffer lights, and I’ve never ever maintained one. They are definitely under the remit of E&P (as they are “high voltage” by the letter of the law) and are ran to failure (ie Not maintained).

 

[snowball]

The February Modern Railways has a piece on blockades of the Watford DC lines to catch up the maintenance backlog. It mentions that the "battery lamps" for the buffer stop lights at Watford Junction, a "bugbear" of Network Rail's Route Director for West Coast South, will be replaced by "electric lights".

 

[Malaxa]

There is an illuminated buffer stop light immediately behind the famous Shenfield Shark. It has been invisible for years.

 

[mr_moo]

There is an illuminated buffer stop light immediately behind the famous Shenfield Shark. It has been invisible for years.

Random point but true - here's a picture I took of it in August 2021: