Class 701 'Aventra' trains: should full power be used in normal operation?

[janahan]

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Class 701 'Aventra' trains for South Western Railway: progress updates

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From a drivers perspective would you say that the companies professional driving policy is possibly restricting the performance of the 701s? I know it’s probably true with all stock but could 701s especially justify an amended, less restrictive policy? (For clarity sake, I know the policy is there for a reason, safety and comfort, and the last thing drivers want is station overshoots, or worse SPADs or buffer stop collisions, but I wonder if the 701s have more to take advantage of without compromising safety or comfort)

Not a train driver, nor anyone associated with the railway, so take what I am about to say as an "ignorant" couch opinion...

If I was trying to utilise these trains to their best, I would probably not plan to use their full capabilities, even if proven to be safe, but instead figure out a reasonable performance curve that should be used in normal cases (it may include things like use 85% of power during accelerating from a standstill for example).

That way, if safe to do so (important), the full performance is still available during abnormal situations (delays) to help bring back a schedule?

 

[pompeyfan]

Not a train driver, nor anyone associated with the railway, so take what i am about to say as an "ignorant" couch opinion! But if I was trying to utilise these trains to their best, I would probably NOT plan to use their full capabilities, even if proven to be safe, but instead figure out a reasonable performance curve that should be used in normal cases, (it may include things like use 85% of power during accelarating from a standstill for example).
That way, if safe to do so (important), the full performance is still available during abnormal situations (delays) to help bring back a schedule?

Whilst I appreciate what you’re saying (as seen in many logistics and transport industries), for train operating companies the policy always has to trump performance and is mandatory, so cannot be broken in an attempt to rectify performance issues. On an airline they’ll usually only use 90% thrust to take off but it’s at the pilots discretion, on the railway drivers MUST be doing a set speed in certain circumstances and if they’re caught pinching a few mph for the sake of performance, it can be taken pretty serious, especially if they have an incident as a direct result of pinching these minutes.

 

[janahan]

Whilst I appreciate what you’re saying (as seen in many logistics and transport industries), for train operating companies the policy always has to trump performance and is mandatory, so cannot be broken in an attempt to rectify performance issues. On an airline they’ll usually only use 90% thrust to take off but it’s at the pilots discretion, on the railway drivers MUST be doing a set speed in certain circumstances and if they’re caught pinching a few mph for the sake of performance, it can be taken pretty serious, especially if they’re caught pinching have an incident as a direct result of pinching these minutes.

Oh, I am not sure if i was clear in my post, but i was deifinately NOT suggesting doing anything wrong like applying speeding, or breaking rules! I was simplying implying that we have an established safe "perfromance" which can including things like acceleration, speed, dwell times, etc, giving the absolute safest running procedure, but then derate it further by a slight amount to give a buffer so that during times of disruption, you have a SAFE headway still available to catch up a little maybe, and this headway and its usage is part of policy!

 

[DMckduck]

Whilst I appreciate what you’re saying (as seen in many logistics and transport industries), for train operating companies the policy always has to trump performance and is mandatory, so cannot be broken in an attempt to rectify performance issues. On an airline they’ll usually only use 90% thrust to take off but it’s at the pilots discretion, on the railway drivers MUST be doing a set speed in certain circumstances and if they’re caught pinching a few mph for the sake of performance, it can be taken pretty serious, especially if they have an incident as a direct result of pinching these minutes.

The good old PDP, followed by boat loads of Please explain the delay.

 

[Bigfoot]

If the line speed for the location and signalling allows there aren't many drivers that won't make full use of the trains capabilities. However as a passenger you only see out the side window, there are many factors at play.

Accelerating hard towards a signal which you will stop at is pointless, slower acceleration hopefully means it will have time to clear and a smoother and overall better journey.

Traveling on a tube that runs under ATO is the worst experience when there are delays in front of you. Full power, full brake. Stop in tunnel, full power etc.

 

[janahan]

If the line speed for the location and signalling allows there aren't many drivers that won't make full use of the trains capabilities. However as a passenger you only see out the side window, there are many factors at play.

Accelerating hard towards a signal which you will stop at is pointless, slower acceleration hopefully means it will have time to clear and a smoother and overall better journey.

Traveling on a tube that runs under ATO is the worst experience when there are delays in front of you. Full power, full brake. Stop in tunnel, full power etc.

probably getting a little off here, but older ATO often still used fixed blocks, and simple mechanics internally, and didnt take into account the speed of the train ahead (the Vic Line was originally created in the 60s, and whilst remarkable for its time, didnt have the processing to do what modern solid state systems can do), therefore it woudl result in the full accelration/stop. Newer ATO are better and controllinging the speed based on more factors, such as the speed of the train ahead, and other factors.

 

[OneTrackMinded]

If the line speed for the location and signalling allows there aren't many drivers that won't make full use of the trains capabilities. However as a passenger you only see out the side window, there are many factors at play.

Even so, drivers will often take a while to get up to a decent percentage. Sometimes it will be 5% for 3 seconds, 50% for 5 seconds, then 85% and a slow rise to somewhere near 100%. Not exactly using the full capability since by the time they reach 100% it’s already 30 or 40 seconds in. And even then a lot seem to only want to go to 80%. Obviously these percentages might not be completely accurate but are based off the speed of full power acceleration compared to slower rates.

 

[pompeyfan]

Oh, I am not sure if i was clear in my post, but i was deifinately NOT suggesting doing anything wrong like applying speeding, or breaking rules! I was simplying implying that we have an established safe "perfromance" which can including things like acceleration, speed, dwell times, etc, giving the absolute safest running procedure, but then derate it further by a slight amount to give a buffer so that during times of disruption, you have a SAFE headway still available to catch up a little maybe, and this headway and its usage is part of policy!

I’m not quite sure you’re understanding what I’m saying.

If a signal is at red at the end of the platform, the policy says 15mph at the platform ramp for example. The train is clearly capable of arriving at the platform faster than that and stopping safely, and this could save cumulative minutes, however if the driver was doing 25 mph at the ramp, then had a SPAD, the driver would be in significant hot water.

There is no way within the professional / defensive driving policy of removing any of these restrictions for the sake of performance or within certain circumstances. Even on clear signals if a driver hit a platform ramp at 50mph and stopped perfectly, driver managers and operational standards would have kittens as it’s inviting risk, even if it’s perfectly within the capabilities of both train and driver.

Getting back to 701s, could the policy be amended to say along the lines of “clear signals you hit the ramp at 35, however if on a 701 you can hit the ramp at 40”

 

[NSEWonderer]

From a drivers perspective would you say that the companies professional driving policy is possibly restricting the performance of the 701s? I know it’s probably true with all stock but could 701s especially justify an amended, less restrictive policy? (For clarity sake, I know the policy is there for a reason, safety and comfort, and the last thing drivers want is station overshoots, or worse SPADs or buffer stop collisions, but I wonder if the 701s have more to take advantage of without compromising safety or comfort)

PDP applies in certain scenarios yes, like you wont take full power up to a restricted signal when departing, a reduced notch is expected here. Approaching Reds and platforms with a Red will change how you brake as you'll be aiming for 15 by the ramp for a platform or 15 for an aws magnet unless like areas of short signalling where you'll get that to 15 quicker.

There are plenty of places and times ive had to test 701s to their potential when driving, you've just got to be more aware that it will get to Line speed much quicker than most and so there's a risk of exceeding line speed if you’re not paying attention because you're used to a certain point doing less than the speed the 701 has got to at that time.

Braking, the main risk imo would be more of a stop short than an overshoot(you'd really have to be completely out of it to do so) as the brakes are really good and thus using braking points for other traction like Desiro will often slow you down faster than need be.

The 701s also allow you at the very worst to put it into emergency and take it out, so long as you dont stop in emergency, you don't report it as per training. But again if you require emergency and it isn't due to low adhesion, you've probably come in too hot and open yourself to a conversation potentially.

In short just depends on the Driver and at times the PDP but only in set conditions, if all is good then I dont mess about with 701s. Might mean you dwell quite abit more however at stations you usually wouldn't!

 

[pompeyfan]

It’s interesting that the use of emergency isn’t reportable unless it also brings the train to a stand. I’m sure if an OTDR download repeated use of this, it would raise eyebrows.

 

[43096]

In short just depends on the Driver and at times the PDP but only in set conditions, if all is good then I dont mess about with 701s. Might mean you dwell quite abit more however at stations you usually wouldn't!

That’s exactly as it should be! It also helps recover from delays - there’s nothing more infuriating than being on a late running service that is getting later because there is no urgency (ie driver driving like an 80 year old ada taking her car to the shops).

 

[NSEWonderer]

It’s interesting that the use of emergency isn’t reportable unless it also brings the train to a stand. I’m sure if an OTDR download repeated use of this, it would raise eyebrows.

It would, and you'd be questioned, but so long as it's not stopped in emergency there isn't a whole lot that can be done. Now if you keep needing emergency without good reason I'm very sure there'd be a serious discussion.

With 701s though, I can't see why you'd use it outside of where conditions or situation require out of the norm. Up to 60% brake is very plenty, often will have to reduce quite a bit if using that.

 

[Bigfoot]

Even so, drivers will often take a while to get up to a decent percentage. Sometimes it will be 5% for 3 seconds, 50% for 5 seconds, then 85% and a slow rise to somewhere near 100%. Not exactly using the full capability since by the time they reach 100% it’s already 30 or 40 seconds in. And even then a lot seem to only want to go to 80%. Obviously these percentages might not be completely accurate but are based off the speed of full power acceleration compared to slower rates.

This completely misses the point that just because you believe the drivers should accelerate hard every single time doesn't mean that it is sensible or safe to do so.

Perhaps tell the driver when you notice them not taking enough power for your liking your opinion on the matter and see how well it goes down.

 

[OneTrackMinded]

This completely misses the point that just because you believe the drivers should accelerate hard every single time doesn't mean that it is sensible or safe to do so.

Perhaps tell the driver when you notice them not taking enough power for your liking your opinion on the matter and see how well it goes down.

I quoted the part of the post which mentioned:

If the line speed for the location and signalling allows there aren't many drivers that won't make full use of the trains capabilities.

…so this is specifically referring to when the line speed is high and there are green signals ahead. To clarify further, I also mean when the conditions and location are the same and you’re getting some drivers being very light on the throttle and a few that actually use the full capacity.

 

[Bikeman78]

That’s exactly as it should be! It also helps recover from delays - there’s nothing more infuriating than being on a late running service that is getting later because there is no urgency (ie driver driving like an 80 year old ada taking her car to the shops).

Not much danger of that on West Anglia. The 317s were thrashed to within an inch of their lives. I assume the 720s are similar, though they will probably be waiting time a lot if the schedules are the same.

 

[notadriver]

The most efficient way to use energy with electric traction is to accelerate as quickly as possible to line speed then coast as long possible line speeds and gradients permitting.

 

[Peter Wilde]

Going back to the title of this thread: another issue - when (if?!) all 90 of the 701 trains are in full, intensive use, is there actually enough power available in the 3rd rail system to allow all of the trains to be driven at the max without any restriction ?