1Y17 Leeds to Nottingham 04.05.26

[Railwaycat]

It was reported on local news two days ago, clearly because RAIB have become involved https://www.bbc.co.uk/news/articles/cwy2xnwpg1go

An investigation is under way after a train reportedly travelled 40mph over the permitted speed in Nottinghamshire, leading to passengers being "thrown" from their seats.

The Rail Accident Investigation Branch said that on 4 May, the 12:09 Leeds to Nottingham service, operated by Northern, was involved in an "overspeeding" incident at Trowell North and South Junctions at about 13:47 BST.

It said the train's speed caused it to lurch sideways, which led to some passengers being "thrown from their seats" and others falling to the floor, resulting in a number of minor injuries.

Having travelled this route many times over the last 60 years (in the 60's some Sheffield - Nottingham services went this way) it's a puzzle how this could have happened given the Ilkeston stop - if it was an EMR service without that stop then it's easy to understand. If it had happened before the junction was reconfigured (conventional double junction, no ladders) then a derailment would have been highly likely. The report conclusions will be interesting.

 

[Dave61]

It was reported on local news two days ago, clearly because RAIB have become involved https://www.bbc.co.uk/news/articles/cwy2xnwpg1go
Having travelled this route many times over the last 60 years (in the 60's some Sheffield - Nottingham services went this way) it's a puzzle how this could have happened given the Ilkeston stop - if it was an EMR service without that stop then it's easy to understand. If it had happened before the junction was reconfigured (conventional double junction, no ladders) then a derailment would have been highly likely. The report conclusions will be interesting.

Unless the driver got confused and thought he was on one of the rare trips that goes via Toton (1Y35, IY34 used to be one ), I have often seen them running that way via the high lines in Long Eaton which we can see from the bedroom window. I think they were/are mostly late at night and I guess are for route knowledge - but lets see what the report brings.

 

[ModernRailways]

Unless the driver got confused and thought he was on one of the rare trips that goes via Toton (1Y35, IY34 used to be one ), I have often seen them running that way via the high lines in Long Eaton which we can see from the bedroom window. I think they were/are mostly late at night and I guess are for route knowledge - but lets see what the report brings.

As already mentioned, the driver does not sign via Toton. Between Sheffield and Nottingham they sign the one route with none of the diversions.

 

[sharpener]

If it had happened before the junction was reconfigured (conventional double junction, no ladders) then a derailment would have been highly likely.

Do you mean it is a conventional double junction now or was one before the remodelling? The only track plan I can find online is this one updated 12/1/2016 (my Quail books are not accessible atm).

 

[saismee]

Do you mean it is a conventional double junction now or was one before the remodelling? The only track plan I can find online is this one updated 12/1/2016 (my Quail books are not accessible atm).

I interpreted it as:
Was a conventional double junction (low speed with a sharp turnout), now uses ladders (higher speed, wider turnout). Happy to be corrected.

 

[Nottingham59]

Do you mean it is a conventional double junction now or was one before the remodelling? The only track plan I can find online is this one updated 12/1/2016 (my Quail books are not accessible atm).

According to openrailwaymap, it is now a conventional double junction from the slow lines towards Nottingham, with parallel tracks and diamond traversed by trains coming from Nottingham.

But the crossover from the fast lines to the slow lines, before the divergence, is a modern (double lead) staircase layout with no diamonds.

So a fast train from Leeds to Nottingham will encounter five switches as it traverses from the Up fast to Down Slow (2), the Down Slow to the Up slow (2), and then the final turnout switch (1).

 

[sharpener]

So a fast train from Leeds to Nottingham will encounter five switches as it traverses from the Up fast to Down Slow (2), the Down Slow to the Up slow (2), and then the final turnout switch (1).

Thanks for that. Which means the train will lurch five times, alternately right then left, this will have thrown the pax about something rotten. Only suprised it didn't lead to a derailment, as the turnouts are all shown as 30mph cf train doing more than twice that.

 

[edwin_m]

According to openrailwaymap, it is now a conventional double junction from the slow lines towards Nottingham, with parallel tracks and diamond traversed by trains coming from Nottingham.

But the crossover from the fast lines to the slow lines, before the divergence, is a modern (double lead) staircase layout with no diamonds.

So a fast train from Leeds to Nottingham will encounter five switches as it traverses from the Up fast to Down Slow (2), the Down Slow to the Up slow (2), and then the final turnout switch (1).

The layout is constrained by the road bridge just north of the actual diverging junction, which still includes the support pier for the elevated building of the onetime Trowell station. This is probably why they used a diamond for the actual junction. Before remodelling circa 2008, and according to my 2006 Quail map, the entire junction was south of the bridge and the slow lines were crossed by four diamonds, two of which were single slips to provide routes between the Goods (now Slow) lines and the Radford line.

Thanks for that. Which means the train will lurch five times, alternately right then left, this will have thrown the pax about something rotten. Only suprised it didn't lead to a derailment, as the turnouts are all shown as 30mph cf train doing more than twice that.

This and the various ECML incidents go to show there is a big margin between overspeeding and actual derailment or track damage, though clearly still a safety hazard from falling people and luggage. I think the severity of the lurches and the risk of derailment depends on the absolute difference between the permitted and actual speeds, not the ratios of the two, and if I recall correctly at least one of the ECML incidents was worse in this respect.

 

[sharpener]

I think the severity of the lurches and the risk of derailment depends on the absolute difference between the permitted and actual speeds, not the ratios of the two

I am supposing the side force cannot exceed a defined fraction of the downward (weight) force before the wheel flanges will start to climb the rails.

IIRC the radial acceleration (=> side force) is proportional to (v^2)/r where v is the speed along the track and r is the radius of the curve.

Hence the risk increases sharply with increasing speed, double the speed will mean 4x the side force. It confirms there is a big safety margin under normal circumstances.

But it does mean that the crew will be thrown about as well. So the driver in the ECML incident can hardly pretend he was unaware of the incident, even a routine move from fast to slow at Digswell can be quite unnerving.

 

[edwin_m]

I am supposing the side force cannot exceed a defined fraction of the downward (weight) force before the wheel flanges will start to climb the rails.

IIRC the radial acceleration (=> side force) is proportional to (v^2)/r where v is the speed along the track and r is the radius of the curve.

Hence the risk increases sharply with increasing speed, double the speed will mean 4x the side force. It confirms there is a big safety margin under normal circumstances.

But it does mean that the crew will be thrown about as well. So the driver in the ECML incident can hardly pretend he was unaware of the incident, even a routine move from fast to slow at Digswell can be quite unnerving.

That all looks accurate to me. I'm beginning to doubt whether my previous statement on absolute versus relative speed difference is correct.

There are two derailment mechanisms, flange climbing as you mention here, and overturning. Which happens first depends on a number of factors including the angle of contact between the flange and the rail, the coefficient of friction between same, and the height of the centre of mass.

 

[sharpener]

There are two derailment mechanisms, flange climbing as you mention here, and overturning.

To be fair I didn't consider overturning. Thinking about it now I imagine the c.g. of a typical train would be quite low and flange climbing the more likely especially where pointwork is involved which would provide a "key" for the movement to start.

Curiously I also found details of the 1988 coal wagon derailment very close nearby which according to one account was initiated by the lead wagon catching on an expansion joint (breather switch mentioned at 2'20").

 

[Merle Haggard]

At the infamous Eltham Well Hall 1972 mishap, about 65 mph into a 20 mph, it appears to me from the accident report (on Railways Archive) that the loco. had the effect initially of straightening the curve (but no flange climb) which doesn't seem to have been considered so far. Possibly the result of a heavy loco (cl 47) with possibly a low centre of gravity and possibly no shoulder ballast to restrain the sleepers

Although probably not relevant to the recent mishaps it does show the size of the side forces generated

 

[edwin_m]

At the infamous Eltham Well Hall 1972 mishap, about 65 mph into a 20 mph, it appears to me from the accident report (on Railways Archive) that the loco. had the effect initially of straightening the curve (but no flange climb) which doesn't seem to have been considered so far. Possibly the result of a heavy loco (cl 47) with possibly a low centre of gravity and possibly no shoulder ballast to restrain the sleepers

Although probably not relevant to the recent mishaps it does show the size of the side forces generated

I don't believe any of the recent turnout overspeed incidents have caused any track damage, so that process is unlikely to be applicable here. The one at Bletchley a few years ago did damage the track I think. At Well Hall the track may have been older with less ballast to keep it in place, whereas all these were modern pointwork with track and ballast probably in good condition.

 

[Amos390]

Been to Notts quite a few times in the last week or so, and every time I have seen a Northern train I have observed 2, maybe 3 people in the cab at one time now, whereas prior to the incident it was only 1. Could this have been one of Norther’s immediate responses to the overspeed?

 

[LowLevel]

Been to Notts quite a few times in the last week or so, and every time I have seen a Northern train I have observed 2, maybe 3 people in the cab at one time now, whereas prior to the incident it was only 1. Could this have been one of Norther’s immediate responses to the overspeed?

No. They'll just be undertaking routine training or assessment duties.

 

[Amos390]

No. They'll just be undertaking routine training or assessment duties.

Ah ok, thanks, just thought it unusual that at least 10 services all had that many people in the cab.

 

[skyhigh]

Could this have been one of Norther’s immediate responses to the overspeed?

The data shows incidents are more likely with more than one person in the cab, so it would be a slightly silly response.

There's just a lot of route learning happening at the moment.