Questions about UK rail operation

[BR111]

Hi all, I have a few questions about things I have noticed in my time travelling with and observing the UK railway, including videos and research on the internet.

1) Is there a reason why to apply Power, you pull the lever towards you, and to brake, you push it away? This seems counterintuitive, and almost every other system I'm aware of (and for sure the one I'm professionally active on), you always push away to apply power/release brakes and pull to apply brakes. It only seems to be the UK doing this, but please correct me on this if I am wrong.

2) Why is there a difference between headlight and marker light? Why is only one headlight on? From what I have discovered, during night operations the left headlight is on to improve visibility of the signals. But why is it the right one during the day? At what point does the driver change between night and day settings? Are other configurations possible, and if so, what/when are they used?

3) The UK 3rd rail tracks have the shoes on top of the rail. How is this handled in case of evacuation or when staff need to leave the train and get on the line, for whatever reason? Is there additional protection in place in areas where the track is frequently accessed, i.e. in depots?

4) When doing route knowledge in the UK, what is assessed? So to what detail do you need to know a route, and how do you know where you are? From what I have seen, there are distance markers, although they don't appear to be always there. And what use are they if you don't have some sort of documentation of what is on the route? For example Station xyz by Mile 5 3/4

5) Does the UK have ay form of in-cab signalling, or is everything AWS and TPWS? Are there routes with ETCS of any level currently in operation?

6) What are the operational duties of a guard? What additional duties must the driver take on when there is no guard, and how often is this the case? I'm assuming this is line and company dependent, but is a driver only operation becoming more common? I was aware that there were guard strikes not all too long ago, but I didn't really pay much attention to the details and the results of the strike

7) When approaching a diverging junction, how much warning do you get to reduce your speed? How do you know when you can speed up again? Are there times when it's entirely down to route knowledge)

8) I've noticed that (true at least for GWR and SWR) 158's seem to consist of 1 1/2 158s...what is the reason for that? Was there a higher demand than anticipated and then they just merged the units together?

Thanks for your time. Undoubtedly as time goes on I will have more questions. How should I handle this - make another topic with a few bundled together like here, or could I just post the new questions on the same thread?

Many thanks for your time

 

[swt_passenger]

8. GWR made 3 car 158s by merging 1 & 1/2 original 2 car, but SWR’s similar trains are all proper 3 car units, 22 x 159/0, and 8 x 159/1. The 159/1 were previously numbered in the 158 series but were also 3 car from new.

 

[ForTheLoveOf]

I can only answer a few of your questions with certainty, but here goes.

5) Does the UK have ay form of in-cab signalling, or is everything AWS and TPWS? Are there routes with ETCS of any level currently in operation?

The vast majority of lines operate on colour signals (a mixture of two, three and four aspect ones), with AWS and TPWS. However, other systems used include semaphore signalling (mostly with AWS and TPWS), "train staff" operation, one-train-in-steam and Radio Electronic Token Block. A few lines have ATP. The only lines under ETCS are, AFAIK, the Cambrian Line and HS1. Everything else is in-cab signalling of some description. ETCS is being introduced on Crossrail and Thameslink core sections, but neither are used in routine passenger operation yet.

I'm assuming this is line and company dependent, but is a driver only operation becoming more common?

It depends on what exactly you're referring to by DOO! Driver open, guard close is probably not totally off the cards for being expanded, but I doubt that, under the current industrial relations situation, 'true' DOO (i.e. the rostering of only one member of staff) will be expanded.

 

[43055]

Hello, I can't answer all your questions but at least its a start.

5. The Transport for Wales 158s has ETCS? for a line in Wales (Shrewsbury to Aberystwyth and Pwlheli) but I think the East Coast Main line is due to be upgraded to allow for 140mph running.

6. Guards normally check and issue tickets, operate doors and announcements and generally look after the passenger's if needed ie helping with luggage or questions on connections.

7.Depends on the junction. Some junctions may show a caution aspect to show the train is diverging and the signal will only clear after a curtain amount of time the train has been in the section before so the train has to slow down.

 

[CC 72100]

Hello BR111 and welcome to the forum. I'll respond to a couple:

3) In sidings that I sign, the 3rd rail is covered by a kickboard - if you imagine the [ to be the kickboard and T to be the 3rd rail, a cross-section diagram would look like [T] . It is therefore very difficult to touch the 3rd rail because of the kickboard - to do so you'd have to stand on top of it.

4) Route knowledge is generally assessed initially when first qualifying over that route ("signing" a route) by an assessed drive over the route and a question paper. Ongoing, it is then assessed during standard assessments, the frequency of which is dependent on the company's individual Competence Management System (CMS). If a driver signs several routes (majority of drivers) then they should be assessed over different routes for each of their assessments, on which the general driving standard and route knowledge can be assessed. Mileposts (distance markers) should be there but are dependent on region. For example, in the Wessex region the mileposts are excellent - reflective, consistently there, not obscured. Get closer to Bristol and they become sporadic and of debatable clarity. You therefore use plenty of other markers to know where you are, such as buildings and other features.

7) This is dependent on how the junction is signalled. For example, for slower speed junction there may use 'approach control' signalling, whereby you are signalled down with the normal signalling sequence and the signal at the junction (the junction signal) will then 'step up' from a red to a proceed aspect once you sight it. That said, you should never expect the signal to step up - it may be red because you are not authorised to proceed like any other stop signal on the network.

Faster is flashing yellows - at the signal preceding the junction signal, you will get a flashing yellow aspect (signifies diverging route and speed reduction required) and a proceed aspect at the junction signal. Interestingly enough I sign 2 junctions that are both 40mph but yet one uses approach control, the other flashing yellows.

For high speed junctions there are splitting distants but they are confusing if you don't use them (I don't) but still have to know them.

Finally you can just get the junction signal without any prior warning, but generally (not always) it is done on a line where the speed is low enough that you could stop in time anyway if you were being wrongly routed.

 

[hexagon789]

1) Is there a reason why to apply Power, you pull the lever towards you, and to brake, you push it away? This seems counterintuitive, and almost every other system I'm aware of (and for sure the one I'm professionally active on), you always push away to apply power/release brakes and pull to apply brakes. It only seems to be the UK doing this, but please correct me on this if I am wrong.

The idea is you push a dangerous situation away from you and thus push the lever for braking. You are right, most other countrues are push for traction power, Northern Ireland's DMUs are set-up like this.

2) Why is there a difference between headlight and marker light? Why is only one headlight on? From what I have discovered, during night operations the left headlight is on to improve visibility of the signals. But why is it the right one during the day? At what point does the driver change between night and day settings? Are other configurations possible, and if so, what/when are they used?

The headlights are high-intensity beam so approaching trains can be easily seen. The reason for having the left headlight for night is to illuminate signage which is normally on the left and so as not to dazzle drivers of oncoming trains. Not sure why the day light is the right one though.

3) The UK 3rd rail tracks have the shoes on top of the rail. How is this handled in case of evacuation or when staff need to leave the train and get on the line, for whatever reason? Is there additional protection in place in areas where the track is frequently accessed, i.e. in depots?

I believe 3rd rail trains carry short-circuiting bars which can be placed on the live rail to short-circuit it and cut traction current, otherwise I imagine a driver would call up the signaller and request a switch off.

4) When doing route knowledge in the UK, what is assessed? So to what detail do you need to know a route, and how do you know where you are? From what I have seen, there are distance markers, although they don't appear to be always there. And what use are they if you don't have some sort of documentation of what is on the route? For example Station xyz by Mile 5 3/4

I believe everything is done on memory, speed restrictions, signals, junctions, braking points etc.

5) Does the UK have ay form of in-cab signalling, or is everything AWS and TPWS? Are there routes with ETCS of any level currently in operation?

Some metro systems, the only 'heavy' rail line with ECTS is the Cambrian in Wales which has it for trial purposes.

When approaching a diverging junction, how much warning do you get to reduce your speed? How do you know when you can speed up again? Are there times when it's entirely down to route knowledge)

Route knowledge; though for really significant reductions in speed trains get checked by the signalling system either virtually to a stand or using flashing aspects.

I hope I've got this all broadly correct. If not I'm sure someone will correct me!

 

[cuccir]

How should I handle this - make another topic with a few bundled together like here, or could I just post the new questions on the same thread?

Best bet is either to post questions as their own thread as they occur, or to post questions together in themed threads eg "Some driving related questions", "Some questions about stock", "Some questions about guards' duties" or whatever: that way you'll get the right people opening the thread to respond!

 

[Bald Rick]

3) for areas with conductor rail, if there needs to be an evacuation of passengers from the train, the power will be switched off. In an extreme emergency, or in the event passengers ‘self evacuate’ the power may still be on, but only for as long as it takes a member of staff to realise there are passenger sgetting off the train, and make a call to the signaller or preferably the electrical control operator.

In sidings, the conductor rail often has kick boards, but not always. Staff are trained to gain a specific competence in working (including walking) near live D.C. equipment as part of the personal track safety training. Finally, in depots, conductor rail is often not present, and trains may be moved around by connection from the shoe gear to an overhead trolley system.

5) ETCS is in use on the Cambrian line, and has been for nearly a decade. Whilst it was done as a ‘early deployment’, it wasn’t a trial as such. ETCS is live on the Thameslink core, although rarely used at present until drivers are trained. ETCS is live on the Hertford Loop for a few miles either side of Watton at Stone, on the down line (northbound) only. This is a test site and not used by service trains. Finally ETCS is about to be deployed in the Heathrow tunnels, and is in the later stages of planning for the south end of the ECML, with the Moorgate Branch first up.

The Crossrail tunnels use a system known as CBTC (Communications Based Train Control), and is similar to the systems applied on many London Underground Lines. Whilst it is related to ETCS, it is definitely not ETCS, and requires a whole different set of equipment on the train.

HS1 is controlled by TVM430, the (former) standard system in use on French High Speed lines. Although the more recent lines use ETCS, and the older lines are now being converted. HS1 will also be converted when the TVM system is due for renewal.

Finally, some parts of the GWML has a form of Automatic Train Protection, which whilst not cab signalling as such (drivers must still obey the signals by the line), it does offer additional advice to the driver in terms of speed control approaching a signal at danger, and will intervene if the advice is not obeyed.

7) plenty. Signaling standards require any divergence with a differential of more than 10mph to involve some form of signalling control, usually through Approach control (signal held at restrictive aspect on approach), or flashing yellows (indicating to the driver that the route is set for a specific divergence). Also, advanced warning boards for the divergent speed limit are provided at no less than braking distance from the junction.

 

[BR111]

Thank you all for your replies! I have read everybody's responses, but there are a few responses I'd like elaboration on:

It depends on what exactly you're referring to by DOO! Driver open, guard close is probably not totally off the cards for being expanded, but I doubt that, under the current industrial relations situation, 'true' DOO (i.e. the rostering of only one member of staff) will be expanded.

I did indeed mean the guard completely being removed from the train. I guess the door closing procedure would be done by using cameras on the train and/or platform so that the driver alone assesses the situation on the platform. Glad to see the trains will remain occupied though. Does that mean every train has a guard in the present?

4) Route knowledge is generally assessed initially when first qualifying over that route ("signing" a route) by an assessed drive over the route and a question paper. Ongoing, it is then assessed during standard assessments, the frequency of which is dependent on the company's individual Competence Management System (CMS). If a driver signs several routes (majority of drivers) then they should be assessed over different routes for each of their assessments, on which the general driving standard and route knowledge can be assessed. Mileposts (distance markers) should be there but are dependent on region. For example, in the Wessex region the mileposts are excellent - reflective, consistently there, not obscured. Get closer to Bristol and they become sporadic and of debatable clarity. You therefore use plenty of other markers to know where you are, such as buildings and other features.

How do you figure out where you are when it's dark and foggy? That seems like a very demanding situation; especially when at speed and where you need to know where the platforms are. And from your answer that means there really is no documentation where you can reference where things on the route are compared to the mileposts?

7) plenty. Signaling standards require any divergence with a differential of more than 10mph to involve some form of signalling control, usually through Approach control (signal held at restrictive aspect on approach), or flashing yellows (indicating to the driver that the route is set for a specific divergence). Also, advanced warning boards for the divergent speed limit are provided at no less than braking distance from the junction.

Are the advanced warning boards always placed? So if I see a flashing yellow, there should also be an advanced warning board with the speed I need to have met by the time I reach the junction?

 

[ForTheLoveOf]

Does that mean every train has a guard in the present?

No; a fair proportion of services in the southeast (around London) only have one member of staff rostered, so this may be considered "true" DOO. This working was mostly introduced before privatisation in 1996-97. Other services, such as a fair proportion of services operated by Southern, have a driver but usually also another member of staff onboard who checks tickets and ensures safety. However, they are not involved in the dispatch process (other than perhaps assisting disabled passengers), so for example they do not need to stop selling tickets when the train is at a station. The same system of working is adopted in a lot of the suburban lines around Glasgow.

 

[ComUtoR]

2) Why is there a difference between headlight and marker light? Why is only one headlight on? From what I have discovered, during night operations the left headlight is on to improve visibility of the signals. But why is it the right one during the day? At what point does the driver change between night and day settings? Are other configurations possible, and if so, what/when are they used?

Most, if not all, of how each unit is built and set up is governed by the RGS (Railway Group Standards) These set out the technical requirements. If memory serves me correct. The minimal requirement is to have 1 headlight and 1 taillight as a minimum. As already described, we use the one on the left as the Night headlight because that reflects the lineside signage and it would potentially dazzle an oncoming Driver at night. The day headlight is to assist in being seen by track workers. Headlights are there for the train to be seen, not specifically to be see by. Part of the reason we have both is to act as a redundancy. If one fails, switch to the other. There is also another headlight, often called the Cyclops eye. This is the one in the center at the top of each unit. The group standards have changed recently so that there is a minimal level of illumination and that yellow fronts are no longer required if a higher level of illumination has been met.

3) Is there additional protection in place in areas where the track is frequently accessed, i.e. in depots?

There seems to be a bit of a difference in what people are believing/stating to be 'depot' For me, as a Driver, the depot is one of many locations I take in a unit, am able to shunt it around, and be able to berth it. This means that the 3rd rail is very much exposed. There are kickboards and we have a new style protection too but much of it is still exposed. I walk around it every day with little concern. 'Depots' in that units are worked on by maintenance is more in keeping in what has been said about trolley supplies. This is because the units are being worked on, like where you mentioned 'workshop/garage'

4) When doing route knowledge in the UK, what is assessed? So to what detail do you need to know a route, and how do you know where you are? From what I have seen, there are distance markers, although they don't appear to be always there. And what use are they if you don't have some sort of documentation of what is on the route? For example Station xyz by Mile 5 3/4

I know my routes quite intimately. There is plenty of documentation to use as reference. We have various route maps, Electronic maps, videos, briefiing documents, and most importantly we have the sectional appendix which is the official documentation of each line of route. This has some of the more technical information about the route.

Finally, in depots, conductor rail is often not present, and trains may be moved around by connection from the shoe gear to an overhead trolley system.

What do you think of as being a 'depot' are you limiting this to a TMD (Maintenence) ? Such as Hornsey and not somewhere like 'Cricklewood' I assume (yeah I know I shouldn't) You would class Cricklewood as a 'Sidings' What about somewhere like 'Grove Park' ?

How do you figure out where you are when it's dark and foggy? That seems like a very demanding situation; especially when at speed and where you need to know where the platforms are.

I can drive by certain shadows at night (its kinda freaky) But there are many many landmarks to navigate by. Anything from a curve inthe track, a specific change of gradient, a Whistle board, Bridge etc etc.

Are the advanced warning boards always placed? So if I see a flashing yellow, there should also be an advanced warning board with the speed I need to have met by the time I reach the junction?

With junctions there is usually a lot of information as has already been described. Some junction you can hit at linespeed. Again, you need to refer back to group standards as to what is required at each location. The more severe the junction, the more information you will get. 'approach control' is also there to act as mitigation for a SPAD. If the speed is reduced by the signalling system it gets protected by TPWS/AWS etc. If you did SPAD then its mitigated. It happens where there is a 'double blocking' where one additional signal is set to red so that when you SPAD that one, you are still protected. Search user 'Sunset Route' and he gives an explanation in another thread.

 

[whhistle]

8) As @swt_passenger said above, the SWR ones are "proper" 3-car units.
You can tell the difference as the 1 and 1/2 units have a cab in the middle car at one end. The SWR units do not (study photos and it becomes easier to see the difference).

 

[Bald Rick]

I did indeed mean the guard completely being removed from the train. I guess the door closing procedure would be done by using cameras on the train and/or platform so that the driver alone assesses the situation on the platform. Glad to see the trains will remain occupied though. Does that mean every train has a guard in the present?

As others have answered, there is no ‘guard’ on a train for Driver Only Operation (nor Driver Controlled Operation). Over half of all U.K. rail passengers are currently conveyed on trains in these circumstances. The most common method of platform dispatch is now by cameras on the train and monitors in the cab, although there are a variety of other methods (platform cameras with platform monitors; platform cameras with on train monitors, mirrors, driver looks back via the window/door, and platform staff dispatch via a ‘Close Doors, Right Away’ (CD/RA) indicator). It is a controversial subject though!

Are the advanced warning boards always placed? So if I see a flashing yellow, there should also be an advanced warning board with the speed I need to have met by the time I reach the junction?

There is a standard about advanced warning boards on plain line and I forget the detail. It is something like an AWB must be placed if the reduction in speed is more than 1/3rd of the current linespeed (ie divergent speed is 66% or less of the main route speed) and that includes if the speed drops in smaller increments over a short distance. @MarkyT will know for sure. I don’t know how that standard applies to divergent junctions, but it won’t be any less restrictrictive. Besides there aren’t that many junctions in the U.K. where the divergent speed is more than 66% of the through speed, except in slow speed areas such as stations.

What do you think of as being a 'depot' are you limiting this to a TMD (Maintenence) ? Such as Hornsey and not somewhere like 'Cricklewood' I assume (yeah I know I shouldn't) You would class Cricklewood as a 'Sidings' What about somewhere like 'Grove Park' ?

By depot I mean main maintenance facility, so TMD or similar. In my mind, everything that isn’t a depot is sidings.

 

[E_Reeves]

For number 1, maybe if the driver collapses onto the control lever then there is more chance of it pushing forward, therefore more chance of applying the brake? Just a though...

 

[MarkyT]

There is a standard about advanced warning boards on plain line and I forget the detail. It is something like an AWB must be placed if the reduction in speed is more than 1/3rd of the current linespeed (ie divergent speed is 66% or less of the main route speed) and that includes if the speed drops in smaller increments over a short distance. @MarkyT will know for sure. I don’t know how that standard applies to divergent junctions, but it won’t be any less restrictrictive. Besides there aren’t that many junctions in the U.K. where the divergent speed is more than 66% of the through speed, except in slow speed areas such as stations.

From: https://www.rssb.co.uk/rgs/standards/GKRT0075 Iss 4.pdf

3.3.1.4 Except where the criteria in 3.3.1.5 apply, a permissible speed warning indicator shall be provided on all signalled approaches to each permissible speed reduction, where either:

a) The permissible speed on the approach, including any differential speed, is 60 mph or greater and the required speed reduction is one-third or more, taking account of any differential permissible speeds that apply, or

b) There are two or more successive reductions in permissible speed within a distance of 3.2 km (2 miles), none of which individually represents a reduction of one-third, but which together require a speed reduction of one-third or more from an approach speed of 60 mph or greater.

3.3.1.5 Permissible speed warning indicators shall not be provided for:

a) A speed reduction over a diverging route where the signalling system is configured to display signal aspects that provide for the required speed reduction (see 3.3.7).

b) A speed reduction over a level crossing where a Level Crossing Warning Sign (St Georges Cross) is provided.

By depot I mean main maintenance facility, so TMD or similar. In my mind, everything that isn’t a depot is sidings.

I think the Southern in particular were fond of erecting 'car sheds' for stabling stock out of use overnight under cover, but they are still just sidings.

 

[hexagon789]

For number 1, maybe if the driver collapses onto the control lever then there is more chance of it pushing forward, therefore more chance of applying the brake? Just a though...

If the driver collapsed the DVD should trigger the DSD and stop the train anyway.

 

[E_Reeves]

If the driver collapsed the DVD should trigger the DSD and stop the train anyway.

It would, yes, but not immediately, especially if the driver's feet stayed on the pedal. If they collapsed onto the lever though, I'd rather the train have a better chance of applying the brakes than accelerating.

 

[hexagon789]

It would, yes, but not immediately, especially if the driver's feet stayed on the pedal. If they collapsed onto the lever though, I'd rather the train have a better chance of apply the brakes than accelerating.

I agree, modern trains have the potential to build up some speed in 60 seconds, though
you would get a full brake application after that though. The danger would be more so on the trains still operating without a DVD only a DSD.

 

[Kneedown]

If the driver collapsed the DVD should trigger the DSD and stop the train anyway.

Not all trains are fitted with Driver Vigilance Device. Even those that are are mostly reset by a movement of the controls, so if a Driver were to collapse over the controls, it could potentially be another minute before the Vilgilance activated and the brakes applied.

 

[TheEdge]

How do you figure out where you are when it's dark and foggy? That seems like a very demanding situation; especially when at speed and where you need to know where the platforms are. And from your answer that means there really is no documentation where you can reference where things on the route are compared to the mileposts?

You are just expected to learn, you learn your markers and make sure you have markers that you can recognise in the dark or in the fog. Things like crossings, signals, bridges, signals, things that will always at least be visible or audible regardless of the conditions, so never use something like a tree or house away from the line. we have either a Route Atlas or Sectional Appendix which both have fulls plans of routes but they are not really something to refer to while driving.

Are the advanced warning boards always placed? So if I see a flashing yellow, there should also be an advanced warning board with the speed I need to have met by the time I reach the junction?

The official figure for advanced warning boards is where the drop in linespeed is more than a third. So 100mph to 50mph would get one, 100mph to 80mph would not. Although its not universal, sometimes you'll get one for a small drop and not for a large. Under flashing yellows you may have a board or you may not, it is just advance warning you are taking a diverging route of a lower speed. As drivers were are expected to know our linespeeds. I drive through a junction where the diverging route is 25mph from a 60mph, its approach controlled (so we get slowed down to a red signal) but between that last red signal and the junction is plenty of distance to get faster than 25mph, but I'm expected to know that if I'm diverging I need to be doing 25.

 

[hexagon789]

Not all trains are fitted with Driver Vigilance Device.

True, but I did state that.

Even those that are are mostly reset by a movement of the controls, so if a Driver were to collapse over the controls, it could potentially be another minute before the Vilgilance activated and the brakes applied.

Exactly, and that's why I said up to 60 seconds. From rest plenty of modern trains could be at 70mph or more and at speed an awful lot faster.

 

[Sleeperwaking]

For number 1, maybe if the driver collapses onto the control lever then there is more chance of it pushing forward, therefore more chance of applying the brake? Just a though...

I have a half memory that this is the reason for the push away to brake, but I've no evidence to support it. Someone once told me that the Railway Rule Book is written in blood - every time there's an accident, the Rule Book (and I suppose the standards) get updated to cover the root cause. If a design change is superseded later on by new requirements, it doesn't necessarily get updated - instead you get layers upon layers of items added to mitigate various hazards (maybe it started with just a requirement to push the lever away to brake, then maybe they added the Driver's Safety Device for situations when the driver didn't collapse on the handle, then added Vigilance for when something was left on the DSD pedal, etc. etc. - note that this sentence is more of an example involving a lot of supposition on my part).

 

[ComUtoR]

By depot I mean main maintenance facility, so TMD or similar. In my mind, everything that isn’t a depot is sidings.

Cheers as always.

It would, yes, but not immediately, especially if the driver's feet stayed on the pedal. If they collapsed onto the lever though, I'd rather the train have a better chance of applying the brakes than accelerating.

As Sleeperwalking has mentioned. The design has evolved over time. When I drove a 508 there was a 'deadmans handle' which you had to push on all the time. Not only would it be possible to fall onto it, people used to hang stuff on it. Now I drive 700s and the differences in design are incredible. The likelyhood of falling onto the handle, randomly getting it pushed or pulled back, falling onto the DSD etc etc are very very slim indeed.

Either push or pull, you are just as likely to grab for something (this being the controller) to prevent yourself from falling over.

 

[Bromley boy]

Are the advanced warning boards always placed? So if I see a flashing yellow, there should also be an advanced warning board with the speed I need to have met by the time I reach the junction?

Not always. For example, I’m aware of a location where the line-speed is 90mph, the highest speed divergent junction is 50mph - so more than 1/3 reduction - the only indication to approaching trains is flashing yellows.

It’s also worth noting that flashing yellows indicate the highest speed divergence at a forthcoming junction.

 

[TRAX]

I agree, modern trains have the potential to build up some speed in 60 seconds, though
you would get a full brake application after that though. The danger would be more so on the trains still operating without a DVD only a DSD.

What are the differences between the DVD and the DSD ?

 

[hexagon789]

What are the differences between the DVD and the DSD ?

The DSD (Driver Safety Device), is the pedal which must be depressed to prevent any emergency brake application (on older DMUs/EMUs it's often incorporated into the power handle which must be held down for the same purpose instead of as a foot pedal).

The DVD (Driver Vigilance Device), is the timer over laid on the DSD which goes off every so often (typically 60 seconds) and must be reset to prevent the DSD applying the brakes. A reset on some stock is done by moving various controls or lifting and then depressing the DSD pedal on some stock only the latter will reset the DVD.

Someone can maybe give specifics of which class had which set-up.

 

[TRAX]

Ah both are interworked - I knew about the DSD but was wondering if the DVD was a different system. Thanks.

 

[MarkyT]

Not always. For example, I’m aware of a location where the line-speed is 90mph, the highest speed divergent junction is 50mph - so more than 1/3 reduction - the only indication to approaching trains is flashing yellows.

To paraphrase the simple case from my previous quote from: https://www.rssb.co.uk/rgs/standards/GKRT0075 Iss 4.pdf
(Railway Group Standard GK/RT0075, Issue Four, Date September 2015, Lineside Signal Spacing and Speed Signage)

A permissible speed warning indicator is provided where the approach speed is 60 mph or greater and the speed reduction is one-third or more, unless the signalling system is configured to display signal aspects that provide for the required speed reduction.

This means that if a lower speed divergence is signalled by means of Main route Approach released from Red (MAR), then that is usually deemed to convey sufficient information for the driver to be able to negotiate the junction safely according to their route knowledge, so an AWI is not (usually) provided. For flashing yellow and splitting distant approaches to fast divergences, AWIs are more likely to be provided but again if those developing the layout determine there's sufficient distance to slow down after reading and fully understanding the junction signal indication then an AWI may not be provided. Your example seems a borderline case. On a very recent scheme I'd have thought an AWI would be provided. It's very easy to provide one co-located with the flashing yellow and it can share the AWS installation so wouldn't be expensive. How old is the signalling in the area concerned?

 

[Bromley boy]

This means that if a lower speed divergence is signalled by means of Main route Approach released from Red (MAR), then that is usually deemed to convey sufficient information for the driver to be able to negotiate the junction safely according to their route knowledge, so an AWI is not (usually) provided. For flashing yellow and splitting distant approaches to fast divergences, AWIs are more likely to be provided but again if those developing the layout determine there's sufficient distance to slow down after reading and fully understanding the junction signal indication then an AWI may not be provided. Your example seems a borderline case. On a very recent scheme I'd have thought an AWI would be provided. It's very easy to provide one co-located with the flashing yellow and it can share the AWS installation so wouldn't be expensive. How old is the signalling in the area concerned?

Thanks for this.

The location in question has prehistoric signalling judging by the appearance of the signal heads themselves (ex southern region, filament bulb, colour light).

Come to think of it the track has recently been relaid and the divergent speed reduced from 60 to 50mph, so is more borderline now than previously!

The same location also has a lower speed (40mph) divergence which is indeed “MAR” controlled.

Out of interest, are PRIs considered to be “signal aspects” for these purposes? Could you dispense with flashing yellows where PRIs had been installed?

 

[ComUtoR]

The reverse end of this route also has flashing yellows. Speed drop from 80mph to 40mph then about 100m onto a 30mph