the sniper
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Which is surely the most extreme possible example, with such short sections and long trains, which bears little resemblance to most of the railway...
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Train Driving Techniques and Instructions
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Which is surely the most extreme possible example, with such short sections and long trains, which bears little resemblance to most of the railway...
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bramling
Veteran Member
The thing here is by trickling up to the red, there is the possibility - in certain locations - that the back of the train will still be occupying a track circuit that it wouldn’t otherwise be occupying, which in turn could be locking up a junction or causing trains behind to encounter more adverse aspects than they otherwise would.
There’s certainly a valid argument which can be constructed to say that safety trumps this, however it still is going to have a performance effect in some locations, justified or not depending on one’s viewpoint.
You can also have the scenario that if the train is further back from the signal then it’s going to take longer to progress forwards once the signal clears. This will be more of an issue if the signal goes straight from red to green, for example at a junction. These seconds again add up, hence one benefit of ATO on metro railways.
Deliberately so, to make it easier to understand.
Annetts key
Established Member
With respect, that is very much dependent on the signal spacing, number and length of track circuits/axle counter sections, design of the track layout (including position of signals, points, clearance points etc.) and the design of the interlocking.
If the timetable has been designed correctly and in accordance with the design of the layout and interlocking, then trains should not routinely encounter red signals except at approach released (approach controlled) signals protecting junctions with a lower speed diverging route or at stations where the train stops anyway.
Excluding faults and incidents, if trains are routinely encountering red signals, either trains are arriving earlier than timetabled, more trains are running than the system was designed for or the trains are running out of sequence. Or the design of the timetable includes a train intentionally having to stop (e.g. to allow for another train to take priority at a junction, loop or station).
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It's an edge case scenario. Thameslink Core and similar are really on the edge of these type situations. You can just as much reduce that exact same scenario with having shorter unit lengths. It's also more limited to Metro driving than mainline. Clearing a junction generally gives you a clear signal in FRONT of you. You reduce your speed on approach to it and then pull away once the junction clears. IF you are approaching a junction at red and that is causing other delays to services behind you because you are at a crazy junction where it clears but are still approaching a red; the brown stuff really has already hit the spinney thing.
We have gone from approaching a red causing a delay, to a unit clearing the overlap and then delaying others because they are still approaching a red.... That is certainly something I am happy to challenge. It's attributional b******s. The blame game is at play here. Using the extreme edge case situations doesn't help where PDPs are detrimental to performance.
Yes. ATO really pushes the limit between safety and performance; and in some cases I would agree. @Bald Rick is acutely aware of the Thameslink network and where ATO does have a benefit; but it is still and edge case where the margins involved are tighter than a ducks proverbial.
Speeds at the magnet are a red herring when it comes to performance attribution. What it is obfuscating is that pathway allowances, sectional running times, approach control, and the safety culture doesn't work together and that it is still a bun fight between Network Rail and the TOCs.
CAF397
Member
There are certain signals that if you are approaching them expecting a red you are crawling until you see them, because they are poorly sighted around a corner or hidden due to lineside structures.
Sometimes (perversely) its overall quicker to run slower approaching the single yellow before it, and get that signal to change to green or two yellows than it is passing the single yellow and slowing for the red.
That might not be reflected in the timeable, but it is a good use of route knowledge and the PDP. I always say a signal at yellow or two yellows can't be SPAD'd. Why would I want to chase red signals?
Sometimes (perversely) its overall quicker to run slower approaching the single yellow before it, and get that signal to change to green or two yellows than it is passing the single yellow and slowing for the red.
That might not be reflected in the timeable, but it is a good use of route knowledge and the PDP. I always say a signal at yellow or two yellows can't be SPAD'd. Why would I want to chase red signals?
thirdraildrive
Member
I mean from my perspective, if a train is coming down to that many red signals that the train ends up delayed more than a minute or so, the problem really isn't how it's being driven, but that doesn't automatically mean the signallers are to blame, it's very complex. Everything is being pushed to the limit of what trains, infrastructure and people can achieve to the point where any reds equals immediate delay. Drivers won't be quick to rush up to a signal for obvious reasons or to instantly take power when one clears, they need to process that that signal does apply to them etc.
On the flip side, I wouldn't expect a signaller to be rushing to clear signals up either, I understand that them rushing to keep lines free of reds and flowing as fast as is humanly possible will inevitably lead to mistakes such as wrong routes being offered; they will take their time to ensure they do the job well and that is more than understandable.
The main issue, in my opinion, is just how far the limits are pushed with timetabling. There is only so many trains that can be out there using all these different intersecting routes before the slightest delay on one causes a huge knock on effect on others and there isn't often space to recover without disruptive action e.g. skipping stations. The issue is timetabling and infrastructure.
I'll add as well I can think of quite a few areas where the timetable simply does not allow enough time to actually make the stops on time. You'll depart on time at station A, drive fast as is safely possible with the traction and conditions available but still arrive late at station B. I'm sure many of you could think of a few yourself too, but the timetable stays the same. On the flip side there will be places you'll have more time than you need and end up sitting at stations or signals waiting because you're early.
In summery I really don't think how drivers or signallers perform is the main issue, yes it can have an effect but it is marginal when compared to the above.
On the flip side, I wouldn't expect a signaller to be rushing to clear signals up either, I understand that them rushing to keep lines free of reds and flowing as fast as is humanly possible will inevitably lead to mistakes such as wrong routes being offered; they will take their time to ensure they do the job well and that is more than understandable.
The main issue, in my opinion, is just how far the limits are pushed with timetabling. There is only so many trains that can be out there using all these different intersecting routes before the slightest delay on one causes a huge knock on effect on others and there isn't often space to recover without disruptive action e.g. skipping stations. The issue is timetabling and infrastructure.
I'll add as well I can think of quite a few areas where the timetable simply does not allow enough time to actually make the stops on time. You'll depart on time at station A, drive fast as is safely possible with the traction and conditions available but still arrive late at station B. I'm sure many of you could think of a few yourself too, but the timetable stays the same. On the flip side there will be places you'll have more time than you need and end up sitting at stations or signals waiting because you're early.
In summery I really don't think how drivers or signallers perform is the main issue, yes it can have an effect but it is marginal when compared to the above.
100%
Except where pathing time comes in, as you say…
But there are faults and incidents, and therefore out of course running ,and therefor red signals.
My point is not that Driving Policies are unnecessary. My points are:
1) changing a driving policy without understanding what that may do to train running performance is asking for trouble
2) having different driving policies for the same situation can’t be right, and is of course not easy to design a signalling system for.
irish_rail
On Moderation
Disagree. We had the 10mph policy at GWR during October and November and in several cases it led me to be having to accelerate towards the red due to gradients etc. Its a daft policy and the decision should be left to the drivers discretion , end of story. My route knowledge is better than that of a manager somewhere who comes out with these dictats.
CAF397
Member
We had a manager have a go at us about 'taking power up to a red'.
That's a very strong statement, made as if to make you feel you'd done something wrong.
When you look at the context - 15mph 200yards from the signal (ie AWS magnet), due to the gradient the train would not get anywhere near the signal, so 1 notch of power was taken to keep the train moving. It wasn't accelerating, it was maintaining the speed to allow the train to proceed closer to the signal.
As you say, someone reads the PDP and sees the power controller take power when soon after the DRA will be set, and they think its all black and white.
While I don't disagree with you regarding reds on gradients, there is a bigger picture here that sometimes gets missed.
Policies like this are often put in place because there is pressure from higher up the food chain to manage risk - from people who potentially could end up in prison when something goes terribly wrong, or who have to answer to directors/shareholders/the DfT when a poor safety record has a negative impact of any kind. Bear in mind that ultimately any organisation like a TOC has a responsibility under the Health & Safety at Work Act to ensure that risk is reduced as low as reasonably practicable - leaving it all to an individual employee's discretion is unlikely to go down very well before a judge.
Therefore, policies - and sometimes the policies lack nuance, agreed - are put in place to demonstrate that risk is being managed proactively. Although in reality this is often reactive (much like a significant proportion of the rule book) - e.g. the collision at Plymouth which led to a flurry of activity around permissive working risk assessments and new instructions for drivers.
There is a lot of nervousness around low adhesion and red signals at the moment following the Salisbury collision, which could have been much, much worse. Purely hypothetically (as we won't know the full details until the RAIB report is published), if there is a prosecution and it came to light that SWR had no instructions to drivers in place despite knowing of the risk of a SPAD and therefore a collision during low adhesion, they wouldn't have a leg to stand on. Please note I am not saying that this was the case, just using it to make the point.
Annetts key
Established Member
And there will continue to be faults and incidents, resulting in delays and out of course running. The problem being that it’s extremely hard to predict and therefore plan in advance for the almost infinite number of variations of the causes of faults and incidents.
Where there is sufficient capacity, that’s the reason why there should be at least some slack in the timetable. But at the same time, having a train waiting unnecessarily is a waste of resources. So it’s a balance that someone has to decide on.
For the vast majority of the Network Rail infrastructure, it’s unlikely that the speed that a train is travelling, at 200 metres on approach to a signal at red, is going to make a significant difference compared to the other causes of delays.
If the signal is red because of faults or incidents or due to disruption due to previous faults or incidents, the root cause is those faults or incidents.
In terms of when signals step up, outside of mechanical signal boxes, in most power signal boxes and more recent signalling centres (whatever they are called), the signaller (or automatic route setting system) can route the signal as soon as the previous train has cleared the junction or points. They don’t have to wait for the previous train to have cleared that whole signal section. Once a route is set, the interlocking will then hold the signal at red and only allow it to clear when it is safe to do so. This part is then automatic, so, happens within a second of the previous train having cleared the section. No further input being needed from the signaller.
On plain line sections, or sections over little used junctions/points, the signals are often specified to be able to be set to work automatically. In this case, once this function is set, there is no further input needed from the signaller no matter how many trains go through this/these signal section(s). The interlocking clearing signals completely automatically as soon as it is safe to do so.
In my experience, when trains are disrupted, it’s the time that it takes for decisions to be made at interchange stations that causes the biggest knock on delays. For example, when it’s decided to re-platform a train. Then you have to wait for all the passengers to walk to the ‘new’ platform, only then can the train be dispatched. It’s similar when the decision is made to terminate a service short and tell the passengers to board a later train. The extra people trying to board the later (likely already late) service will further delay it.
In order to reduce failures and delays, it does mean that the railways have to stop being driven by cost cutting (all areas, be it going for cheaper, but lower quality or less reliable equipment, equipment that is harder to repair or service on site, not reducing redundant (backup) systems, cutting maintenance, reducing staff levels, attacking the T&Cs and working practices of the staff). And instead plan for and invest in both more reliable and quality equipment, and invest in the staff.
I’ll end it there, as this is drifting off topic.
The point being, the situation is often far more complex than it appears.
Well you aren't disagreeing with me then. My overall point is that you won't occur many delays if you come up slower. As a driver I will also judge each signal differently. I'm not advocating for anyone to go faster or slower, but indeed approach the signal as they see fit. My point is at least on my routes and diagrams that I almost certainly aren't causing a delay coming up slower and won't be pressured to go any faster.
hexagon789
Veteran Member
Something I've often wondered, with the often more aggressive (perhaps more like here before the defensive driving policies came in, rather than actively aggressive per se) driving in other European countries - do any of them have modified braking instructions for low adhesion?
How do they deal with it.
I can't say I've noticed French or Swiss drivers brake any lighter in poor weather, but then I'm not a driver - I notice more than the average punter but I don't have that additional knowledge or feel to perceive everything that another driver might.
Just curious, I've often wondered about it when defensive driving policies or poor adhesion is discussed on the forum.
How do they deal with it.
I can't say I've noticed French or Swiss drivers brake any lighter in poor weather, but then I'm not a driver - I notice more than the average punter but I don't have that additional knowledge or feel to perceive everything that another driver might.
Just curious, I've often wondered about it when defensive driving policies or poor adhesion is discussed on the forum.
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