Salisbury train crash, cause of accident revealed
Discussion
Blimey, sounds like a bit of a defective track layout / signalling arrangement if overshooting one signal can send you careering at speed into another train?
"The inquiry found the SWR train was travelling at 86mph - which was within the speed limit - as it approached a stop signal near Fisherton Tunnel.
When the driver applied the brakes, the train's wheels 'began to slide almost immediately'.
The train slid 191m past the signal until it hit the side of the GWR service. The interim report found that the signalling system was 'operating as designed'."
https://www.dailymail.co.uk/news/article-10535315/...
"The inquiry found the SWR train was travelling at 86mph - which was within the speed limit - as it approached a stop signal near Fisherton Tunnel.
When the driver applied the brakes, the train's wheels 'began to slide almost immediately'.
The train slid 191m past the signal until it hit the side of the GWR service. The interim report found that the signalling system was 'operating as designed'."
https://www.dailymail.co.uk/news/article-10535315/...
Im a train driver so have abit of knowledge around this subject
So the wheels slipped because of leaves on the line.
The signal would have been protected by a safety system TPWS (train protection warning system) the safety system works by gauging the trains speed and if the train is deemed to be going too fast it will initiate an emergency brake application on the trainthat the driver is unable to over ride. The train will then come to a stop within a predetermined overlap between signals but far enough apart from other trains, that is assuming the trains brakes are managing to work.
Unfortunately due to the fact the wheels were already sliding uncontrollably, braking harder had no effect. And the train ran through the signal and into another train.
Usually during autumn rails are pressure washed and or traction gel applied, I have no idea if this happened.
Some trains also lay sand when the wheels start to slip to help traction, again i couldn't comment if it was equipped or operational on the train involved In the accident.
So the wheels slipped because of leaves on the line.
The signal would have been protected by a safety system TPWS (train protection warning system) the safety system works by gauging the trains speed and if the train is deemed to be going too fast it will initiate an emergency brake application on the trainthat the driver is unable to over ride. The train will then come to a stop within a predetermined overlap between signals but far enough apart from other trains, that is assuming the trains brakes are managing to work.
Unfortunately due to the fact the wheels were already sliding uncontrollably, braking harder had no effect. And the train ran through the signal and into another train.
Usually during autumn rails are pressure washed and or traction gel applied, I have no idea if this happened.
Some trains also lay sand when the wheels start to slip to help traction, again i couldn't comment if it was equipped or operational on the train involved In the accident.
Largechris said:
Blimey, sounds like a bit of a defective track layout / signalling arrangement if overshooting one signal can send you careering at speed into another train?
"The inquiry found the SWR train was travelling at 86mph - which was within the speed limit - as it approached a stop signal near Fisherton Tunnel.
When the driver applied the brakes, the train's wheels 'began to slide almost immediately'.
The train slid 191m past the signal until it hit the side of the GWR service. The interim report found that the signalling system was 'operating as designed'."
https://www.dailymail.co.uk/news/article-10535315/...
I doubt it's practical to signal every junction such that it's totally safe when the rails are contaminated and very slippery."The inquiry found the SWR train was travelling at 86mph - which was within the speed limit - as it approached a stop signal near Fisherton Tunnel.
When the driver applied the brakes, the train's wheels 'began to slide almost immediately'.
The train slid 191m past the signal until it hit the side of the GWR service. The interim report found that the signalling system was 'operating as designed'."
https://www.dailymail.co.uk/news/article-10535315/...
Reading between the lines of the RAIB report, it seems they are quite interested in the speed of the train that overshot the signal. I.e, while it was running within the permitted linespeed (86mph vs 90), should it have been restricted to a lower speed, given the conditions ? The maintenance train ("RHTT") that treats the rails to remove leaf contamination hadn't run that day, for example.
The driver should have been driving to the conditions, braking earlier etc, but the conditions should never be that bad that you over run a signal by nearly 200 meters.
It would be the equivalent to driving sensibly as you know its cold and the roads are greasy with grit, to suddenly hitting a section of black ice that hasnt been treated, you can't plan for that.
It would be the equivalent to driving sensibly as you know its cold and the roads are greasy with grit, to suddenly hitting a section of black ice that hasnt been treated, you can't plan for that.
Simpo Two said:
Cakey_ said:
Unfortunately due to the fact the wheels were already sliding uncontrollably, braking harder had no effect.
How about anti-lock brakes?191 metres doesn't seem a lot of distance between the protecting signal and the junction/points it's protecting, especially
if line speed is 80+mph.
Simpo Two said:
Cakey_ said:
Unfortunately due to the fact the wheels were already sliding uncontrollably, braking harder had no effect.
How about anti-lock brakes?Driving on contaminated rails is almost identical to sheet ice, there's just nothing.
The train driver should have been expecting the signal to be at red since the last signal he had passed would have been at amber and he would have an indication of that in the cab. Railway signals are not like traffic lights.
He should have been aware of conditions and braking a little earlier than normal.
Sound like he slipped up.
On the railway if you go through a red signal (SPAD) then there WILL be either (1)a train in the next section or (2) a set of points against you. That is why the signal is at red.
He should have been aware of conditions and braking a little earlier than normal.
Sound like he slipped up.
On the railway if you go through a red signal (SPAD) then there WILL be either (1)a train in the next section or (2) a set of points against you. That is why the signal is at red.
He would've likely slipped from the first cautionary signal he received if it slid that far than there's clearly a bigger problem than the driver.
Like I said earlier, TPWS would've intervened and stopped the train in the over lap if wheel slip hadn't occurred.
Also not always is there something behind a red, couple of times a week I get stopped at a red because the signaller has forgotten to pull it off
Like I said earlier, TPWS would've intervened and stopped the train in the over lap if wheel slip hadn't occurred.
Also not always is there something behind a red, couple of times a week I get stopped at a red because the signaller has forgotten to pull it off
IJWS15 said:
The train driver should have been expecting the signal to be at red since the last signal he had passed would have been at amber and he would have an indication of that in the cab. Railway signals are not like traffic lights.
He should have been aware of conditions and braking a little earlier than normal.
Sound like he slipped up.
On the railway if you go through a red signal (SPAD) then there WILL be either (1)a train in the next section or (2) a set of points against you. That is why the signal is at red.
The driver would have been unaware of the railhead conditions until he started to brake. You can't tell by looking at the rails. And there are no amber signals on the railway.He should have been aware of conditions and braking a little earlier than normal.
Sound like he slipped up.
On the railway if you go through a red signal (SPAD) then there WILL be either (1)a train in the next section or (2) a set of points against you. That is why the signal is at red.
RAIB interim report is here: https://www.gov.uk/government/news/interim-report-...
IJWS15 said:
The train driver should have been expecting the signal to be at red since the last signal he had passed would have been at amber and he would have an indication of that in the cab. Railway signals are not like traffic lights.
He should have been aware of conditions and braking a little earlier than normal.
Sound like he slipped up.
On the railway if you go through a red signal (SPAD) then there WILL be either (1)a train in the next section or (2) a set of points against you. That is why the signal is at red.
The driver did nothing wrong at all-the train operating company praised his actions after the incident.He should have been aware of conditions and braking a little earlier than normal.
Sound like he slipped up.
On the railway if you go through a red signal (SPAD) then there WILL be either (1)a train in the next section or (2) a set of points against you. That is why the signal is at red.
There’s also a lot more different reasons as to why there’s a signal at danger in front of you than just the two quoted above.
For the train to slide as far as it did, there’s no way it could have been anticipated the rail head conditions were that extreme.
Cakey_ said:
He would've likely slipped from the first cautionary signal he received if it slid that far than there's clearly a bigger problem than the driver.
Like I said earlier, TPWS would've intervened and stopped the train in the over lap if wheel slip hadn't occurred.
Also not always is there something behind a red, couple of times a week I get stopped at a red because the signaller has forgotten to pull it off
Just to understand, this was the driver passing a red, so would he not already have passed a double and single yellow on the two previous blocks? Should you be approaching a red - even from I don’t know, 500m away when he first saw it, at 80mph? Genuine question.Like I said earlier, TPWS would've intervened and stopped the train in the over lap if wheel slip hadn't occurred.
Also not always is there something behind a red, couple of times a week I get stopped at a red because the signaller has forgotten to pull it off
Largechris said:
Cakey_ said:
He would've likely slipped from the first cautionary signal he received if it slid that far than there's clearly a bigger problem than the driver.
Like I said earlier, TPWS would've intervened and stopped the train in the over lap if wheel slip hadn't occurred.
Also not always is there something behind a red, couple of times a week I get stopped at a red because the signaller has forgotten to pull it off
Just to understand, this was the driver passing a red, so would he not already have passed a double and single yellow on the two previous blocks? Should you be approaching a red - even from I don’t know, 500m away when he first saw it, at 80mph? Genuine question.Like I said earlier, TPWS would've intervened and stopped the train in the over lap if wheel slip hadn't occurred.
Also not always is there something behind a red, couple of times a week I get stopped at a red because the signaller has forgotten to pull it off
In over a mile the trains speed reduced by 30mph.
That kind of railhead contamination the driver has got zero chance.
Network rail should get the blame for not running the treatment train earlier but it's easier to blame the driver than the organisation.
Largechris said:
Cakey_ said:
He would've likely slipped from the first cautionary signal he received if it slid that far than there's clearly a bigger problem than the driver.
Like I said earlier, TPWS would've intervened and stopped the train in the over lap if wheel slip hadn't occurred.
Also not always is there something behind a red, couple of times a week I get stopped at a red because the signaller has forgotten to pull it off
Just to understand, this was the driver passing a red, so would he not already have passed a double and single yellow on the two previous blocks? Should you be approaching a red - even from I don’t know, 500m away when he first saw it, at 80mph? Genuine question.Like I said earlier, TPWS would've intervened and stopped the train in the over lap if wheel slip hadn't occurred.
Also not always is there something behind a red, couple of times a week I get stopped at a red because the signaller has forgotten to pull it off
I'd imagine he braked at the first cautionary signal wether that had been 2 yellows or the single yellow.
The point you are missing is my comment that driving on contaminated rails is similar to driving on Ice.
You wouldn't approach a junction at 40mph in a car but if you locked up 1/2 mile before hand and continued to slide than its out of your control. And not necessarily your fault, we can drive to the conditions but can't anticipate the sort of low adhesion that driver experience.
The Mad Monk said:
Why don't thr railway companies/Network Rail, or whatever they are called this week remove all trees or other leaf bearing growth within 50 yards of the rails?
If you look at railways sixty years, or so, ago the cuttings and embankments were all kept well trimmed. I guess to prevent lineside fires from sparks and cinders, but also stop engines losing traction. But nowadays as you say the lineside is very overgrown. Good for nature, not good for trains.Gassing Station | Boats, Planes & Trains | Top of Page | What's New | My Stuff