Recliner <recliner.usenet@gmail.com> wrote:
> Anna Noyd-Dryver <anna@noyd-dryver.com> wrote:
>> Roland Perry <roland@perry.co.uk> wrote:
>>
>>>
>>> How fast was the train going, or do you have "no idea, really"?
>>>
>>> It's almost exactly 800m from the next station were it would stop, and
>>> the previous station is 4.5 miles away, transit time 9mins, so that's an
>>> average of 30mph (yes the cruising speed will be more, but not vastly
>>> so).
>>>
>>>
>>
>> From the clues available in the picture (white house, trackside hut) and
>> also what's not visible (two pylons behind the photographer), the location
>> is around halfway along the straight alongside the Haddiscoe Cut <Dropped
>> pin
>> https://goo.gl/maps/Ba6QPUDY4wF3LgpA8>
>>
>> Linespeed is 20mph across Reedham swing bridge then 60 mph through the
>> non-derailment site and Haddiscoe station then drops to 30mph for
>> Somerleyton swing bridge.
>>
>> It’s around 2.5 miles between the speed increase and the station, so I'd
>> fully expect the train to reach 60mph. Around 1.5 miles from the station, I
>> don't think the driver would be braking yet.
>>
>
> So the stopping distance would be several hundred metres?
>
>

Depending on the train brakes etc, 3-400m I guess. Plus maybe a bit longer
if the driver just shuts off and brakes gently to begin with whilst working
out what the 'something not quite right ahead' actually is; 'straight to
emergency' every time you see something untoward isn't a great strategy!

Anna Noyd-Dryver

On 20/02/2022 11:15, Anna Noyd-Dryver wrote:
> Recliner <recliner.usenet@gmail.com> wrote:
>> Anna Noyd-Dryver <anna@noyd-dryver.com> wrote:
>>> Roland Perry <roland@perry.co.uk> wrote:
>>>
>>>>
>>>> How fast was the train going, or do you have "no idea, really"?
>>>>
>>>> It's almost exactly 800m from the next station were it would stop, and
>>>> the previous station is 4.5 miles away, transit time 9mins, so that's an
>>>> average of 30mph (yes the cruising speed will be more, but not vastly
>>>> so).
>>>>
>>>>
>>>
>>> From the clues available in the picture (white house, trackside hut) and
>>> also what's not visible (two pylons behind the photographer), the location
>>> is around halfway along the straight alongside the Haddiscoe Cut <Dropped
>>> pin
>>> https://goo.gl/maps/Ba6QPUDY4wF3LgpA8>
>>>
>>> Linespeed is 20mph across Reedham swing bridge then 60 mph through the
>>> non-derailment site and Haddiscoe station then drops to 30mph for
>>> Somerleyton swing bridge.
>>>
>>> It’s around 2.5 miles between the speed increase and the station, so I'd
>>> fully expect the train to reach 60mph. Around 1.5 miles from the station, I
>>> don't think the driver would be braking yet.
>>>
>>
>> So the stopping distance would be several hundred metres?
>>
>>
>
> Depending on the train brakes etc, 3-400m I guess. Plus maybe a bit longer
> if the driver just shuts off and brakes gently to begin with whilst working
> out what the 'something not quite right ahead' actually is; 'straight to
> emergency' every time you see something untoward isn't a great strategy!
>
>
> Anna Noyd-Dryver
>
This accident happened at about 8.00am on 30/1/22 not long after sunrise
what would the visibility have been like at that time. Do we know if the
driver had been warned of the possibility of flooding and was perhaps
proceeding slowly?

ian

--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

In message <sus5aj$fgn$2@dont-email.me>, at 01:25:39 on Sun, 20 Feb
2022, Anna Noyd-Dryver <anna@noyd-dryver.com> remarked:
>Roland Perry <roland@perry.co.uk> wrote:
>
>>
>> How fast was the train going, or do you have "no idea, really"?
>>
>> It's almost exactly 800m from the next station were it would stop, and
>> the previous station is 4.5 miles away, transit time 9mins, so that's an
>> average of 30mph (yes the cruising speed will be more, but not vastly
>> so).
>
>From the clues available in the picture (white house, trackside hut) and
>also what's not visible (two pylons behind the photographer), the location
>is around halfway along the straight alongside the Haddiscoe Cut <Dropped
>pin
>https://goo.gl/maps/Ba6QPUDY4wF3LgpA8>

You don't think it's the hut 260m north-east of the bridge (which would
be a handy place to take the photos from)?

There's also this bunker in shot:

<https://i.dailymail.co.uk/1s/2022/01/30/18/53556259-10457643-image-a-29
_1643569181496.jpg>

So: https://goo.gl/maps/HLxC82rRBqFT17iY7

>Linespeed is 20mph across Reedham swing bridge then 60 mph through the
>non-derailment site and Haddiscoe station then drops to 30mph for
>Somerleyton swing bridge.
>
>It’s around 2.5 miles between the speed increase and the station, so I'd
>fully expect the train to reach 60mph. Around 1.5 miles from the station, I
>don't think the driver would be braking yet.

Meanwhile, on the more general point about rail tension, droop, and
sideways displacement, the other track here is showing very little
displacement in *any* direction:

<https://i.dailymail.co.uk/1s/2022/01/30/18/53556263-10457643-image-m-23
_1643568862268.jpg?

The track the train is on, is drooping because of the weight of the
front bogie.

And four sleepers ahead of the front of the train is a rail joint, so
maybe it wasn't quite as tensioned as earlier thought (but still
tensioned enough not to veer off sideways, I think).
--
Roland Perry

In message <sur5ir$a4l$2@dont-email.me>, at 16:23:55 on Sat, 19 Feb
2022, Recliner <recliner.usenet@gmail.com> remarked:
>Roland Perry <roland@perry.co.uk> wrote:
>> In message <sur0p8$3r9$1@dont-email.me>, at 15:02:00 on Sat, 19 Feb
>> 2022, Tweed <usenet.tweed@gmail.com> remarked:
>>> Roland Perry <roland@perry.co.uk> wrote:
>>>> In message <suqrj1$pnd$1@dont-email.me>, at 13:33:21 on Sat, 19 Feb
>>>> 2022, Tweed <usenet.tweed@gmail.com> remarked:
>>>>> Roland Perry <roland@perry.co.uk> wrote:
>>>>>> In message <f94r0hp65iijl7tac2c6m5440vjfkav864@4ax.com>, at 00:08:29 on
>>>>>> Thu, 17 Feb 2022, Charles Ellson <charlesellson@btinternet.com>
>>>>>> remarked:
>>>>>>> On Wed, 16 Feb 2022 14:34:57 +0000, Roland Perry <roland@perry.co.uk>
>>>>>>> wrote:
>>>>>>>
>>>>>>>> In message <sugq0l$cql$1@dont-email.me>, at 18:05:09 on Tue, 15 Feb
>>>>>>>> 2022, Tweed <usenet.tweed@gmail.com> remarked:
>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> Just curious: which laws of physics were violated?
>>>>>>>>>>
>>>>>>>>>> Force acting on a body, causing motion.
>>>>>>>>>
>>>>>>>>> Downward force against a slope produces a lateral component.
>>>>>>>>
>>>>>>>> Even when most of the slope has eroded away, so as not to be touching
>>>>>>>> the bottom of the sleepers any more?
>>>>>>>>
>>>>>>> If your erosion is not in a uniform manner then you will get a
>>>>>>> variable result from the vertical forces applied at different places.
>>>>>>
>>>>>> To zig-zag requires lateral forces, not vertical ones.
>>>>>>
>>>>>>>> In any event, given the tension in the rails, to "twang" them sideways
>>>>>>>> would take, in my opinion, more than the horizontal component of that
>>>>>>>> gravitational pull downwards.
>>>>>
>>>>> A slope is a handy means of converting vertical forces into lateral ones.
>>>>
>>>> But it's not a slope, it's porridge. Flowing down and sideways.
>>>>
>>>> Even the Daily Mail said so: "Water had washed away stones which were
>>>> supporting the track". No support, so it goes down, not sideways.
>>>
>>> Unless it’s a pure liquid there will still be a conversion of vertical to
>>> lateral force.
>>
>> Only briefly, while it's still in contact with the bottom of the
>> sleepers.
>
>It was clearly long enough to slew the track before the train got there.
>Eventually, the whole lot washed away, long after the train stopped. So the
>horizontal displacement probably lasted for hours, not the milliseconds you
>seem to be assuming.

I'm not sure it was *ever* displaced (as a result of the ground washing
away).

>> What's the coefficient of friction between (ahem) rolling
>> stones, and sleepers, anyway?
>
>They weren't rolling.

Whoosh!

>The whole top of the embankment, including the ballast and track, was
>sliding down the slope.

I don't think so.
--
Roland Perry

In message <1cms0htsrrl2dvi8q8qn7eh093is2urqfl@4ax.com>, at 14:26:52 on
Thu, 17 Feb 2022, Recliner <recliner.usenet@gmail.com> remarked:
>On Thu, 17 Feb 2022 13:57:37 +0000, Roland Perry <roland@perry.co.uk> wrote:
>
>>In message <sujf4u$70b$1@dont-email.me>, at 18:18:06 on Wed, 16 Feb
>>2022, Tweed <usenet.tweed@gmail.com> remarked:
>>>Sam Wilson <ukr@dummy.wislons.fastmail.co.uk> wrote:
>>>> Roland Perry <roland@perry.co.uk> wrote:
>>>>> In message <suj76u$r50$1@dont-email.me>, at 16:02:38 on Wed, 16 Feb
>>>>> 2022, martin.coffee@round-midnight.org.uk remarked:
>>>>>> On 16/02/2022 14:31, Roland Perry wrote:
>>>>>>> In message <suhai3$p7q$1@dont-email.me>, at 22:47:32 on Tue, 15 Feb
>>>>>>> 2022, ColinR <rail@greystane.shetland.co.uk> remarked:
>>>>>>>> On 15/02/2022 17:00, Roland Perry wrote:
>>>>>>>>> In message <suebst$vsp$1@dont-email.me>, at 19:51:57 on Mon, 14 Feb
>>>>>>>>> 2022, Anna Noyd-Dryver <anna@noyd-dryver.com> remarked:
>>>>>>>>>>>>> It would also help for you to re-cite any photos/links you
>>>>>>>>>>>>>believe  were posted before the train arrived, so we can see
>>>>>>>>>>>>>if the track was kinked already.
>>>>>>>>>>>>
>>>>>>>>>>>> Why on earth would anyone have happened to be flying a drone
>>>>>>>>>>>>around  that particular area before the train (non-
>>>>>>>>>>>>)derailment? The only such pictures would be from the
>>>>>>>>>>>>train's FFCCTV, and until the RAIB report on the matter,
>>>>>>>>>>>>we're unlikely to see that.
>>>>>>>>>>>
>>>>>>>>>>> I agree that I don't know why such a photo would be available.
>>>>>>>>>>>But it's crucial to the assertion that the zig-zag in the
>>>>>>>>>>>track was there before the train arrived, rather than being
>>>>>>>>>>>caused *by* its arrival.
>>>>>>>>>>
>>>>>>>>>> You still haven't said where this has been asserted.
>>>>>>>
>>>>>>>>>  Recliner has been banging on about it ad nauseam, with his "slid
>>>>>>>>> sideways" due to track-bed erosion theories.
>>>>>>>>
>>>>>>>> I think that you will actually find that Recliner's views are the
>>>>>>>> views of the majority, you are the ONLY outlier.
>>>>>
>>>>>>> Only within the people commenting here, and absolutely none have
>>>>>>> (unless I missed it) come up with a plausible engineering reason why
>>>>>>> the tension in the rails didn't keep them straight, when the ground
>>>>>>> below had eroded away.
>>>>>
>>>>>>> To move (or stay) sideways there has to be a substantial sideways
>>>>>>> force. Where is it coming from?
>>>>>>
>>>>>> Gravity.
>>>>>
>>>>> Which acts downwards, not sideways.
>>>>>
>>>>> If the rails were in compression (I suspect everyone would agree this is
>>>>> extraordinarily unlikely) then when the ground subsides away, that
>>>>> compression force could cause the track to kink, now that there's no
>>>>> ballast holding it in place.
>>>>>
>>>>> Or even if it was neutral, the ground falling away would put the track
>>>>> into tension (because it's stretched due to the dip), which would tend
>>>>> to resist any sideways motion.
>>>>>
>>>>> But I think it's under tension.
>>>>
>>>> IIUC you have a wide-ranging engineering education, so if the rails are
>>>> going to stay straight in the horizontal plane, and are under tension but
>>>> free to move in the vertical plane, can you tell us how big would the dip
>>>> be, and how close would the train driver have to be before it was visible?
>>>
>>>Imagine an elastic band under tension (rails) then imagine hanging some
>>>weights on the elastic band at intervals (sleepers). Imagine putting all
>>>this on a flat surface (intact track bed). Now take a section of that flat
>>>surface and tilt it at 45 degrees. What do you think will happen to the
>>>weights on that 45 degree slope?
>>
>>The track will rotate, but quite soon (way before 45 degrees, more like
>>10 degrees) the ground on the lower side will no longer be in contact
>>with the sleepers.
>
>Of course it will! The track and sleepers sag with the ground. You
>seem to think that the rail tension is far higher than it is.

My theory is the tension, such as it was, prevented sideways motion. I
even estimated the sag.

>> Any sideways motion of the track can therefore only
>>be a result of the component of gravity acting on the remaining contact,
>>not because the ground on the lower side is "pulled" the track with it
>>(that's where the soil mechanics aspect comes in) and it failed to twang
>>back.
>
>Wrong. The sideways motion of the track was caused by the sideways
>motion of the slipping ground, which the track followed as it sagged
>down with the ground.

It didn't move sideways for that reason.

>>The tweeted photo <https://twitter.com/ianhardie9018/status/148778339566
>>0869633?s=21> however shows a void under that side too. Which is why the
>>sequence of events is important.
>
>Yes, that shot was taken later. Eventually, the track was completed
>unsupported, and sagged down (contrary to your theory that the track us
>under such high tension that it remains ramrod straight).

You are misdirecting yourself. I didn't say the track would remain
straight in both planes (a lack of understanding of vertical vs
horizontal has plagued this thread from the start).

>>I remain of the view that the kink shown there wasn't caused by the
>>track sliding sideways "downhill", because tension in the rails would
>>prevent that. Rather it's caused by the deceleration and subsequent
>>static weight of the train.
>
>The driver must have seen the slewed track long before the train got
>close enough to affect it, so your theories of the train causing the
>slewing make no sense.

He could only see slewed (by the subsiding ground) if it had indeed
slewed because of that. My theory is what slew there is was caused by
the drag of the train's brakes.

See also today's subhread where the other track hasn't slewed at all.
--
Roland Perry

In message <suk4nk$66v$1@dont-email.me>, at 00:26:29 on Thu, 17 Feb
2022, Recliner <recliner.usenet@gmail.com> remarked:
>Roland Perry <roland@perry.co.uk> wrote:
>> In message <sugq0l$cql$1@dont-email.me>, at 18:05:09 on Tue, 15 Feb
>> 2022, Tweed <usenet.tweed@gmail.com> remarked:
>>
>>>>>
>>>>> Just curious: which laws of physics were violated?
>>>>
>>>> Force acting on a body, causing motion.
>>>
>>> Downward force against a slope produces a lateral component.
>>
>> Even when most of the slope has eroded away, so as not to be touching
>> the bottom of the sleepers any more?
>
>That was later in the cycle. As you have been repeatedly told, the sideways
>movement happened when the embankment first started slipping to the right
>and dragged the track with it.
>
>Anna posted a tweeted photo in this thread that clearly illustrated this.
>As you still appear unable to find it, here it is again:
><https://pbs.twimg.com/media/FKW719VX0AAUoku?format=jpg&name=large>

That fairly early picture confirms what I've been saying. The track over
the void isn't displaced sideways at all. Just the track under the
train's front bogie, on ground that had not yet been washed away (or
sloping sideways).
--
Roland Perry

On 20/02/2022 15:18, Roland Perry wrote:
> In message <sur5ir$a4l$2@dont-email.me>, at 16:23:55 on Sat, 19 Feb
> 2022, Recliner <recliner.usenet@gmail.com> remarked:
>> Roland Perry <roland@perry.co.uk> wrote:
>>> In message <sur0p8$3r9$1@dont-email.me>, at 15:02:00 on Sat, 19 Feb
>>> 2022, Tweed <usenet.tweed@gmail.com> remarked:
>>>> Roland Perry <roland@perry.co.uk> wrote:
>>>>> In message <suqrj1$pnd$1@dont-email.me>, at 13:33:21 on Sat, 19 Feb
>>>>> 2022, Tweed <usenet.tweed@gmail.com> remarked:
>>>>>> Roland Perry <roland@perry.co.uk> wrote:
>>>>>>> In message <f94r0hp65iijl7tac2c6m5440vjfkav864@4ax.com>, at
>>>>>>> 00:08:29 on
>>>>>>> Thu, 17 Feb 2022, Charles Ellson <charlesellson@btinternet.com>
>>>>>>> remarked:
>>>>>>>> On Wed, 16 Feb 2022 14:34:57 +0000, Roland Perry
>>>>>>>> <roland@perry.co.uk>
>>>>>>>> wrote:
>>>>>>>>
>>>>>>>>> In message <sugq0l$cql$1@dont-email.me>, at 18:05:09 on Tue, 15
>>>>>>>>> Feb
>>>>>>>>> 2022, Tweed <usenet.tweed@gmail.com> remarked:
>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> Just curious: which laws of physics were violated?
>>>>>>>>>>>
>>>>>>>>>>> Force acting on a body, causing motion.
>>>>>>>>>>
>>>>>>>>>> Downward force against a slope produces a lateral component.
>>>>>>>>>
>>>>>>>>> Even when most of the slope has eroded away, so as not to be
>>>>>>>>> touching
>>>>>>>>> the bottom of the sleepers any more?
>>>>>>>>>
>>>>>>>> If your erosion is not in a uniform manner then you will get a
>>>>>>>> variable result from the vertical forces applied at different
>>>>>>>> places.
>>>>>>>
>>>>>>> To zig-zag requires lateral forces, not vertical ones.
>>>>>>>
>>>>>>>>> In any event, given the tension in the rails, to "twang" them
>>>>>>>>> sideways
>>>>>>>>> would take, in my opinion, more than the horizontal component
>>>>>>>>> of that
>>>>>>>>> gravitational pull downwards.
>>>>>>
>>>>>> A slope is a handy means of converting vertical forces into
>>>>>> lateral ones.
>>>>>
>>>>> But it's not a slope, it's porridge. Flowing down and sideways.
>>>>>
>>>>> Even the Daily Mail said so: "Water had washed away stones which were
>>>>> supporting the track". No support, so it goes down, not sideways.
>>>>
>>>> Unless it’s a pure liquid there will still be a conversion of
>>>> vertical to
>>>> lateral force.
>>>
>>> Only briefly, while it's still in contact with the bottom of the
>>> sleepers.
>>
>> It was clearly long enough to slew the track before the train got there.
>> Eventually, the whole lot washed away, long after the train stopped.
>> So the
>> horizontal displacement probably lasted for hours, not the
>> milliseconds you
>> seem to be assuming.
>
> I'm not sure it was *ever* displaced (as a result of the ground washing
> away).
>
>>> What's the coefficient of friction between (ahem) rolling
>>> stones, and sleepers, anyway?
>>
>> They weren't rolling.
>
> Whoosh!
>

Someone's been gathering moss without satisfaction.

--
Graeme Wall
This account not read.

Roland Perry <roland@perry.co.uk> wrote:
> In message <sus5aj$fgn$2@dont-email.me>, at 01:25:39 on Sun, 20 Feb
> 2022, Anna Noyd-Dryver <anna@noyd-dryver.com> remarked:
>> Roland Perry <roland@perry.co.uk> wrote:
>>
>>>
>>> How fast was the train going, or do you have "no idea, really"?
>>>
>>> It's almost exactly 800m from the next station were it would stop, and
>>> the previous station is 4.5 miles away, transit time 9mins, so that's an
>>> average of 30mph (yes the cruising speed will be more, but not vastly
>>> so).
>>
>> From the clues available in the picture (white house, trackside hut) and
>> also what's not visible (two pylons behind the photographer), the location
>> is around halfway along the straight alongside the Haddiscoe Cut <Dropped
>> pin
>> https://goo.gl/maps/Ba6QPUDY4wF3LgpA8>
>
> You don't think it's the hut 260m north-east of the bridge (which would
> be a handy place to take the photos from)?
>
> There's also this bunker in shot:
>
> <https://i.dailymail.co.uk/1s/2022/01/30/18/53556259-10457643-image-a-29
> _1643569181496.jpg>
>
> So: https://goo.gl/maps/HLxC82rRBqFT17iY7
>

Yes I think you're right; the white building in shot is further from the
line than the one I identified on the map.

Still around 1km from the station, could easily still be running at
50-60mph, though I don't know local habits.

>> Linespeed is 20mph across Reedham swing bridge then 60 mph through the
>> non-derailment site and Haddiscoe station then drops to 30mph for
>> Somerleyton swing bridge.
>>
>> It’s around 2.5 miles between the speed increase and the station, so I'd
>> fully expect the train to reach 60mph. Around 1.5 miles from the station, I
>> don't think the driver would be braking yet.
>
> Meanwhile, on the more general point about rail tension, droop, and
> sideways displacement, the other track here is showing very little
> displacement in *any* direction:
>
> <https://i.dailymail.co.uk/1s/2022/01/30/18/53556263-10457643-image-m-23
> _1643568862268.jpg?
>
> The track the train is on, is drooping because of the weight of the
> front bogie.
>
> And four sleepers ahead of the front of the train is a rail joint, so
> maybe it wasn't quite as tensioned as earlier thought (but still
> tensioned enough not to veer off sideways, I think).

Good spot, it's jointed bullhead rail so no (intentional!) tension at all.

Anna Noyd-Dryver

In message <suu39r$8l7$2@dont-email.me>, at 19:03:23 on Sun, 20 Feb
2022, Anna Noyd-Dryver <anna@noyd-dryver.com> remarked:
>Roland Perry <roland@perry.co.uk> wrote:
>> In message <sus5aj$fgn$2@dont-email.me>, at 01:25:39 on Sun, 20 Feb
>> 2022, Anna Noyd-Dryver <anna@noyd-dryver.com> remarked:
>>> Roland Perry <roland@perry.co.uk> wrote:
>>>
>>>>
>>>> How fast was the train going, or do you have "no idea, really"?
>>>>
>>>> It's almost exactly 800m from the next station were it would stop, and
>>>> the previous station is 4.5 miles away,

Correction, between the stations is 4 miles.

>>>>transit time 9mins, so that's an average of 30mph (yes the cruising
>>>>speed will be more, but not vastly so).
>>>
>>> From the clues available in the picture (white house, trackside hut) and
>>> also what's not visible (two pylons behind the photographer), the location
>>> is around halfway along the straight alongside the Haddiscoe Cut <Dropped
>>> pin
>>> https://goo.gl/maps/Ba6QPUDY4wF3LgpA8>
>>
>> You don't think it's the hut 260m north-east of the bridge (which would
>> be a handy place to take the photos from)?
>>
>> There's also this bunker in shot:
>>
>> <https://i.dailymail.co.uk/1s/2022/01/30/18/53556259-10457643-image-a-29
>> _1643569181496.jpg>
>>
>> So: https://goo.gl/maps/HLxC82rRBqFT17iY7
>
>Yes I think you're right; the white building in shot is further from the
>line than the one I identified on the map.
>
>Still around 1km from the station, could easily still be running at
>50-60mph, though I don't know local habits.

Maybe we can look at the timetable again.

If it's 20mph as far as the Reedham swing bridge, that's 1.5km (sorry
about the mixed units) and hence a little under a mile, so maybe three
minutes. Then it's 2.5 miles to the site, plus half a mile to the next
station.

If we take a minute off the timetabled 9mins to account for station
dwell time, that leaves five minutes do the three miles from swing
bridge to station. Average of 36mph I think.

Given you are leaning towards quite late braking for such a station, I
don't think the cruising speed will be much above 40mph. Unless it
always dwells at the stations for longer than the timetable suggests.

>>> Linespeed is 20mph across Reedham swing bridge then 60 mph through the
>>> non-derailment site and Haddiscoe station then drops to 30mph for
>>> Somerleyton swing bridge.
>>>
>>> It’s around 2.5 miles between the speed increase and the station, so I'd
>>> fully expect the train to reach 60mph. Around 1.5 miles from the station, I
>>> don't think the driver would be braking yet.
>>
>> Meanwhile, on the more general point about rail tension, droop, and
>> sideways displacement, the other track here is showing very little
>> displacement in *any* direction:
>>
>> <https://i.dailymail.co.uk/1s/2022/01/30/18/53556263-10457643-image-m-23
>> _1643568862268.jpg?
>>
>> The track the train is on, is drooping because of the weight of the
>> front bogie.
>>
>> And four sleepers ahead of the front of the train is a rail joint, so
>> maybe it wasn't quite as tensioned as earlier thought (but still
>> tensioned enough not to veer off sideways, I think).
>
>Good spot, it's jointed bullhead rail so no (intentional!) tension at all.

How much does such a joint expand and contract normally? We know it was
cold, so could be towards the "shrinking" end of its play. And then the
droop will pull the joint even further apart.

The infamous zigzag pictured in only one of the media, would also be
facilitated by the braking of the train pulling the joint(s) beneath the
train (about one per carriage-length I think, but perhaps someone can
confirm) a bit further apart than normal, and pushing the one just ahead
of the train perhaps into compression.
--
Roland Perry

Roland Perry <roland@perry.co.uk> wrote:
> In message <suu39r$8l7$2@dont-email.me>, at 19:03:23 on Sun, 20 Feb
> 2022, Anna Noyd-Dryver <anna@noyd-dryver.com> remarked:
>> Roland Perry <roland@perry.co.uk> wrote:
>>> In message <sus5aj$fgn$2@dont-email.me>, at 01:25:39 on Sun, 20 Feb
>>> 2022, Anna Noyd-Dryver <anna@noyd-dryver.com> remarked:
>>>> Roland Perry <roland@perry.co.uk> wrote:
>>>>
>>>>>
>>>>> How fast was the train going, or do you have "no idea, really"?
>>>>>
>>>>> It's almost exactly 800m from the next station were it would stop, and
>>>>> the previous station is 4.5 miles away,
>
> Correction, between the stations is 4 miles.
>
>>>>> transit time 9mins, so that's an average of 30mph (yes the cruising
>>>>> speed will be more, but not vastly so).
>>>>
>>>> From the clues available in the picture (white house, trackside hut) and
>>>> also what's not visible (two pylons behind the photographer), the location
>>>> is around halfway along the straight alongside the Haddiscoe Cut <Dropped
>>>> pin
>>>> https://goo.gl/maps/Ba6QPUDY4wF3LgpA8>
>>>
>>> You don't think it's the hut 260m north-east of the bridge (which would
>>> be a handy place to take the photos from)?
>>>
>>> There's also this bunker in shot:
>>>
>>> <https://i.dailymail.co.uk/1s/2022/01/30/18/53556259-10457643-image-a-29
>>> _1643569181496.jpg>
>>>
>>> So: https://goo.gl/maps/HLxC82rRBqFT17iY7
>>
>> Yes I think you're right; the white building in shot is further from the
>> line than the one I identified on the map.
>>
>> Still around 1km from the station, could easily still be running at
>> 50-60mph, though I don't know local habits.
>
> Maybe we can look at the timetable again.
>
> If it's 20mph as far as the Reedham swing bridge, that's 1.5km (sorry
> about the mixed units) and hence a little under a mile, so maybe three
> minutes. Then it's 2.5 miles to the site, plus half a mile to the next
> station.
>
> If we take a minute off the timetabled 9mins to account for station
> dwell time, that leaves five minutes do the three miles from swing
> bridge to station. Average of 36mph I think.
>

I very much think that the train speed would get up to 60mph in the three
miles between the swing bridge and the station. Reference: I get up to
65-70mph between two stops which are 2.5 miles apart, and I suspect that
FLIRTs accelerate faster.

> Given you are leaning towards quite late braking for such a station, I
> don't think the cruising speed will be much above 40mph. Unless it
> always dwells at the stations for longer than the timetable suggests.
>

I don't consider 50-60mph at 1km from the station to be particularly late
braking; it's the standard approach to Port Talbot in both directions, for
example (using that example because approach speed is around 60mph (having
coasted a little from the 70mph linespeed) and the braking point is easily
identifiable on Google maps).

It may be that local practice is to already be braking for the station by
the location of the incident, in which case speed may have been around
50mph or so.

>>>> Linespeed is 20mph across Reedham swing bridge then 60 mph through the
>>>> non-derailment site and Haddiscoe station then drops to 30mph for
>>>> Somerleyton swing bridge.
>>>>
>>>> It’s around 2.5 miles between the speed increase and the station, so I'd
>>>> fully expect the train to reach 60mph. Around 1.5 miles from the station, I
>>>> don't think the driver would be braking yet.
>>>
>>> Meanwhile, on the more general point about rail tension, droop, and
>>> sideways displacement, the other track here is showing very little
>>> displacement in *any* direction:
>>>
>>> <https://i.dailymail.co.uk/1s/2022/01/30/18/53556263-10457643-image-m-23
>>> _1643568862268.jpg?
>>>
>>> The track the train is on, is drooping because of the weight of the
>>> front bogie.
>>>
>>> And four sleepers ahead of the front of the train is a rail joint, so
>>> maybe it wasn't quite as tensioned as earlier thought (but still
>>> tensioned enough not to veer off sideways, I think).
>>
>> Good spot, it's jointed bullhead rail so no (intentional!) tension at all.
>
> How much does such a joint expand and contract normally? We know it was
> cold, so could be towards the "shrinking" end of its play. And then the
> droop will pull the joint even further apart.
>

Around 1/4"-1/2" per joint, OTTOMH.

> The infamous zigzag pictured in only one of the media, would also be
> facilitated by the braking of the train pulling the joint(s) beneath the
> train (about one per carriage-length I think, but perhaps someone can
> confirm) a bit further apart than normal, and pushing the one just ahead
> of the train perhaps into compression.

I know bullhead rail isn't held as tightly to the sleepers as flat-bottomed
rail, especially with wooden keys; but I'd be very surprised if emergency
braking of a one train would move it longitudinally sufficiently to alter
the rail joint gaps.

Anna Noyd-Dryver

Anna Noyd-Dryver <anna@noyd-dryver.com> wrote:
> Roland Perry <roland@perry.co.uk> wrote:
>> In message <suu39r$8l7$2@dont-email.me>, at 19:03:23 on Sun, 20 Feb
>> 2022, Anna Noyd-Dryver <anna@noyd-dryver.com> remarked:
>>> Roland Perry <roland@perry.co.uk> wrote:
>>>> In message <sus5aj$fgn$2@dont-email.me>, at 01:25:39 on Sun, 20 Feb
>>>> 2022, Anna Noyd-Dryver <anna@noyd-dryver.com> remarked:
>>>>> Roland Perry <roland@perry.co.uk> wrote:
>>>>>
>>>>>>
>>>>>> How fast was the train going, or do you have "no idea, really"?
>>>>>>
>>>>>> It's almost exactly 800m from the next station were it would stop, and
>>>>>> the previous station is 4.5 miles away,
>>
>> Correction, between the stations is 4 miles.
>>
>>>>>> transit time 9mins, so that's an average of 30mph (yes the cruising
>>>>>> speed will be more, but not vastly so).
>>>>>
>>>>> From the clues available in the picture (white house, trackside hut) and
>>>>> also what's not visible (two pylons behind the photographer), the location
>>>>> is around halfway along the straight alongside the Haddiscoe Cut <Dropped
>>>>> pin
>>>>> https://goo.gl/maps/Ba6QPUDY4wF3LgpA8>
>>>>
>>>> You don't think it's the hut 260m north-east of the bridge (which would
>>>> be a handy place to take the photos from)?
>>>>
>>>> There's also this bunker in shot:
>>>>
>>>> <https://i.dailymail.co.uk/1s/2022/01/30/18/53556259-10457643-image-a-29
>>>> _1643569181496.jpg>
>>>>
>>>> So: https://goo.gl/maps/HLxC82rRBqFT17iY7
>>>
>>> Yes I think you're right; the white building in shot is further from the
>>> line than the one I identified on the map.
>>>
>>> Still around 1km from the station, could easily still be running at
>>> 50-60mph, though I don't know local habits.
>>
>> Maybe we can look at the timetable again.
>>
>> If it's 20mph as far as the Reedham swing bridge, that's 1.5km (sorry
>> about the mixed units) and hence a little under a mile, so maybe three
>> minutes. Then it's 2.5 miles to the site, plus half a mile to the next
>> station.
>>
>> If we take a minute off the timetabled 9mins to account for station
>> dwell time, that leaves five minutes do the three miles from swing
>> bridge to station. Average of 36mph I think.
>>
>
> I very much think that the train speed would get up to 60mph in the three
> miles between the swing bridge and the station. Reference: I get up to
> 65-70mph between two stops which are 2.5 miles apart, and I suspect that
> FLIRTs accelerate faster.
>
>> Given you are leaning towards quite late braking for such a station, I
>> don't think the cruising speed will be much above 40mph. Unless it
>> always dwells at the stations for longer than the timetable suggests.
>>
>
> I don't consider 50-60mph at 1km from the station to be particularly late
> braking; it's the standard approach to Port Talbot in both directions, for
> example (using that example because approach speed is around 60mph (having
> coasted a little from the 70mph linespeed) and the braking point is easily
> identifiable on Google maps).
>
> It may be that local practice is to already be braking for the station by
> the location of the incident, in which case speed may have been around
> 50mph or so.
>
>>>>> Linespeed is 20mph across Reedham swing bridge then 60 mph through the
>>>>> non-derailment site and Haddiscoe station then drops to 30mph for
>>>>> Somerleyton swing bridge.
>>>>>
>>>>> It’s around 2.5 miles between the speed increase and the station, so I'd
>>>>> fully expect the train to reach 60mph. Around 1.5 miles from the station, I
>>>>> don't think the driver would be braking yet.
>>>>
>>>> Meanwhile, on the more general point about rail tension, droop, and
>>>> sideways displacement, the other track here is showing very little
>>>> displacement in *any* direction:
>>>>
>>>> <https://i.dailymail.co.uk/1s/2022/01/30/18/53556263-10457643-image-m-23
>>>> _1643568862268.jpg?
>>>>
>>>> The track the train is on, is drooping because of the weight of the
>>>> front bogie.
>>>>
>>>> And four sleepers ahead of the front of the train is a rail joint, so
>>>> maybe it wasn't quite as tensioned as earlier thought (but still
>>>> tensioned enough not to veer off sideways, I think).
>>>
>>> Good spot, it's jointed bullhead rail so no (intentional!) tension at all.
>>
>> How much does such a joint expand and contract normally? We know it was
>> cold, so could be towards the "shrinking" end of its play. And then the
>> droop will pull the joint even further apart.
>>
>
> Around 1/4"-1/2" per joint, OTTOMH.
>
>> The infamous zigzag pictured in only one of the media, would also be
>> facilitated by the braking of the train pulling the joint(s) beneath the
>> train (about one per carriage-length I think, but perhaps someone can
>> confirm) a bit further apart than normal, and pushing the one just ahead
>> of the train perhaps into compression.
>
> I know bullhead rail isn't held as tightly to the sleepers as flat-bottomed
> rail, especially with wooden keys; but I'd be very surprised if emergency
> braking of a one train would move it longitudinally sufficiently to alter
> the rail joint gaps.
>
>
> Anna Noyd-Dryver
>

Keys in Bullhead track where there are double or tracks are inserted on the
side of the chair that is facing the normal direction of approach, this is
done so any forces caused by braking that may produce rail creep will pull
the keys into the chair and grip the rail tighter ,though the keys are not
wedge shaped the general friction caused by rust and muck makes them behave
that way.

ISTR that jointed bullhead isn’t under any tension , wasn’t it one of the
jobs of PW staff to keep the fishplate bolts lubricated enough the movement
of a rail due to temperature changes just opened and closed the gaps with
not effect on the joining rail. However you would not want rails so loose
in the chairs that forces from the train wheels either from propulsion or
braking is sliding the rails forward and back. You would end up with quite
noisy track as the rails butted up on adjacent ones as gaps closed up at
one end or the other and the wear on fishplate blots would shorten their
life.

GH

On 01/02/2022 14:20, Anna Noyd-Dryver wrote:
> GB <NOTsomeone@microsoft.invalid> wrote:
>> On 31/01/2022 13:43, Recliner wrote:
>>> On Mon, 31 Jan 2022 13:31:11 +0000, Roland Perry <roland@perry.co.uk> wrote:
>>>
>>>> In message <st8l2g$8md$1@dont-email.me>, at 12:35:28 on Mon, 31 Jan
>>>> 2022, Recliner <recliner.usenet@gmail.com> remarked:
>>>>> Graham Harrison <edward.harrisom.one@btinternet.com> wrote:
>>>>>>
>>>>>> https://www.dailymail.co.uk/news/article-10457643/Train-driver-avoids-d
>>>>>> erailment-leaving-cab-dangling-track-damaged-floodwater.html?ito=native
>>>>>> _share_article-masthead
>>>>>> I'm not a fan of the Daily Mail but ........
>>>>>
>>>>> https://twitter.com/ianhardie9018/status/1487783395660869633?s=21
>>>>
>>>> That shows a significantly bigger sideways displacement than the earlier
>>>> photos. I wonder how much of that was "push" from the braking train (I
>>>> think the rogue water flow was the opposite direction).
>>>
>>> Yes, it does give the impression that it was derailed. I think the
>>> sagging track may have slewed towards the water, and
>>> the first bogie entered that section.
>>
>>
>> There was a suggestion on Twitter that the driver could have reversed,
>> but if I'd been the driver, I think that I'd have been very happy just
>> to get everybody off the train safely. Including myself!
>>
>
> Yes, you definitely wouldn't be moving that train without authority from NR
> and various people watching the affected bogie to make sure it didn't
> misbehave! And you also wouldn't be doing it without that authorisation etc
> because every action you take is recorded.
>
>
> Anna Noyd-Dryver
>
Some real facts at last

https://www.gov.uk/government/news/train-running-onto-a-washed-out-section-of-line-near-haddiscoe

ian

--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

On 22/02/2022 11:17, ianb wrote:
> On 01/02/2022 14:20, Anna Noyd-Dryver wrote:
>> GB <NOTsomeone@microsoft.invalid> wrote:
>>> On 31/01/2022 13:43, Recliner wrote:
>>>> On Mon, 31 Jan 2022 13:31:11 +0000, Roland Perry
>>>> <roland@perry.co.uk> wrote:
>>>>
>>>>> In message <st8l2g$8md$1@dont-email.me>, at 12:35:28 on Mon, 31 Jan
>>>>> 2022, Recliner <recliner.usenet@gmail.com> remarked:
>>>>>> Graham Harrison <edward.harrisom.one@btinternet.com> wrote:
>>>>>>>
>>>>>>> https://www.dailymail.co.uk/news/article-10457643/Train-driver-avoids-d
>>>>>>>
>>>>>>> erailment-leaving-cab-dangling-track-damaged-floodwater.html?ito=native
>>>>>>>
>>>>>>> _share_article-masthead
>>>>>>> I'm not a fan of the Daily Mail but ........
>>>>>>
>>>>>> https://twitter.com/ianhardie9018/status/1487783395660869633?s=21
>>>>>
>>>>> That shows a significantly bigger sideways displacement than the
>>>>> earlier
>>>>> photos. I wonder how much of that was "push" from the braking train (I
>>>>> think the rogue water flow was the opposite direction).
>>>>
>>>> Yes, it does give the impression that it was derailed. I think the
>>>> sagging track may have slewed towards the water, and
>>>> the first bogie entered that section.
>>>
>>>
>>> There was a suggestion on Twitter that the driver could have reversed,
>>> but if I'd been the driver, I think that I'd have been very happy just
>>> to get everybody off the train safely. Including myself!
>>>
>>
>> Yes, you definitely wouldn't be moving that train without authority
>> from NR
>> and various people watching the affected bogie to make sure it didn't
>> misbehave! And you also wouldn't be doing it without that
>> authorisation etc
>> because every action you take is recorded.
>>
>>
>> Anna Noyd-Dryver
>>
>  Some real facts at last
>
> https://www.gov.uk/government/news/train-running-onto-a-washed-out-section-of-line-near-haddiscoe
>

Interesting that both ideas mentioned in this thread are neither supported.

1. Most people have said that the line slid sideways due to the ballast
washing away on one side before the other and before the train's arrival.
2. Roland's view that the sideways must have been a result of the
train's braking and that the track would have stayed straight without a
train's arrival.

The report quotes "Over the next twenty minutes the flowing water caused
all support for the track to be lost and the track sank significantly,
causing the front carriage to tilt forwards and sideways."

This makes it clear that the sideways movement occurs after the train
had stopped so neither 1 nor 2 above happened!

--
Colin

In message <suvkbg$j5d$1@dont-email.me>, at 09:00:32 on Mon, 21 Feb
2022, Anna Noyd-Dryver <anna@noyd-dryver.com> remarked:
>Roland Perry <roland@perry.co.uk> wrote:
>> In message <suu39r$8l7$2@dont-email.me>, at 19:03:23 on Sun, 20 Feb
>> 2022, Anna Noyd-Dryver <anna@noyd-dryver.com> remarked:
>>> Roland Perry <roland@perry.co.uk> wrote:
>>>> In message <sus5aj$fgn$2@dont-email.me>, at 01:25:39 on Sun, 20 Feb
>>>> 2022, Anna Noyd-Dryver <anna@noyd-dryver.com> remarked:
>>>>> Roland Perry <roland@perry.co.uk> wrote:
>>>>>
>>>>>>
>>>>>> How fast was the train going, or do you have "no idea, really"?
>>>>>>
>>>>>> It's almost exactly 800m from the next station were it would stop, and
>>>>>> the previous station is 4.5 miles away,
>>
>> Correction, between the stations is 4 miles.
>>
>>>>>> transit time 9mins, so that's an average of 30mph (yes the cruising
>>>>>> speed will be more, but not vastly so).
>>>>>
>>>>> From the clues available in the picture (white house, trackside hut) and
>>>>> also what's not visible (two pylons behind the photographer), the location
>>>>> is around halfway along the straight alongside the Haddiscoe Cut <Dropped
>>>>> pin
>>>>> https://goo.gl/maps/Ba6QPUDY4wF3LgpA8>
>>>>
>>>> You don't think it's the hut 260m north-east of the bridge (which would
>>>> be a handy place to take the photos from)?
>>>>
>>>> There's also this bunker in shot:
>>>>
>>>> <https://i.dailymail.co.uk/1s/2022/01/30/18/53556259-10457643-image-a-29
>>>> _1643569181496.jpg>
>>>>
>>>> So: https://goo.gl/maps/HLxC82rRBqFT17iY7
>>>
>>> Yes I think you're right; the white building in shot is further from the
>>> line than the one I identified on the map.
>>>
>>> Still around 1km from the station, could easily still be running at
>>> 50-60mph, though I don't know local habits.
>>
>> Maybe we can look at the timetable again.
>>
>> If it's 20mph as far as the Reedham swing bridge, that's 1.5km (sorry
>> about the mixed units) and hence a little under a mile, so maybe three
>> minutes. Then it's 2.5 miles to the site, plus half a mile to the next
>> station.
>>
>> If we take a minute off the timetabled 9mins to account for station
>> dwell time, that leaves five minutes do the three miles from swing
>> bridge to station. Average of 36mph I think.
>
>I very much think that the train speed would get up to 60mph in the three
>miles between the swing bridge and the station. Reference: I get up to
>65-70mph between two stops which are 2.5 miles apart, and I suspect that
>FLIRTs accelerate faster.

Yes, but how many minutes is that? The timetable doesn't require the
trains to sprint between stations, and wait a couple of minutes until
it's time to leave. Perhaps they just drive in a more relaxed fashion,
knowing they will still be "on time".

Later... we now know the train was going sufficiently slowly that the
driver could see water ahead, and stop in time.

>> How much does such a joint expand and contract normally? We know it was
>> cold, so could be towards the "shrinking" end of its play. And then the
>> droop will pull the joint even further apart.
>
>Around 1/4"-1/2" per joint, OTTOMH.

Thanks.
--
Roland Perry

In message <sv2gnq$eu9$1@dont-email.me>, at 11:17:14 on Tue, 22 Feb
2022, ianb <i.bidwell@ntlworld.com> remarked:
>On 01/02/2022 14:20, Anna Noyd-Dryver wrote:
>> GB <NOTsomeone@microsoft.invalid> wrote:
>>> On 31/01/2022 13:43, Recliner wrote:
>>>> On Mon, 31 Jan 2022 13:31:11 +0000, Roland Perry
>>>><roland@perry.co.uk> wrote:
>>>>
>>>>> In message <st8l2g$8md$1@dont-email.me>, at 12:35:28 on Mon, 31 Jan
>>>>> 2022, Recliner <recliner.usenet@gmail.com> remarked:
>>>>>> Graham Harrison <edward.harrisom.one@btinternet.com> wrote:
>>>>>>>
>>>>>>> https://www.dailymail.co.uk/news/article-10457643/Train-driver-avoids-d
>>>>>>> erailment-leaving-cab-dangling-track-damaged-floodwater.html?ito=native
>>>>>>> _share_article-masthead
>>>>>>> I'm not a fan of the Daily Mail but ........
>>>>>>
>>>>>> https://twitter.com/ianhardie9018/status/1487783395660869633?s=21
>>>>>
>>>>> That shows a significantly bigger sideways displacement than the earlier
>>>>> photos. I wonder how much of that was "push" from the braking train (I
>>>>> think the rogue water flow was the opposite direction).
>>>>
>>>> Yes, it does give the impression that it was derailed. I think the
>>>> sagging track may have slewed towards the water, and
>>>> the first bogie entered that section.
>>>
>>>
>>> There was a suggestion on Twitter that the driver could have reversed,
>>> but if I'd been the driver, I think that I'd have been very happy just
>>> to get everybody off the train safely. Including myself!
>>>
>> Yes, you definitely wouldn't be moving that train without authority
>>from NR
>> and various people watching the affected bogie to make sure it didn't
>> misbehave! And you also wouldn't be doing it without that authorisation etc
>> because every action you take is recorded.
>> Anna Noyd-Dryver
>>
> Some real facts at last
>
>https://www.gov.uk/government/news/train-running-onto-a-washed-out-secti
>on-of-line-near-haddiscoe

OK, so it was a dip (into which water had collected), after all: "As the
train approached the section of track concerned, the driver of the train
noticed what appeared to be standing water on the line ahead and started
braking."

And "Over the next twenty minutes the flowing water caused all support
for the track to be lost and the track sank significantly", so no
significant amount of gravity causing the track to slide sideways, *by
the time the train arrived*.
--
Roland Perry

In message <sv2ncj$uh7$1@dont-email.me>, at 13:10:45 on Tue, 22 Feb
2022, ColinR <rail@greystane.shetland.co.uk> remarked:
>On 22/02/2022 11:17, ianb wrote:
>> On 01/02/2022 14:20, Anna Noyd-Dryver wrote:
>>> GB <NOTsomeone@microsoft.invalid> wrote:
>>>> On 31/01/2022 13:43, Recliner wrote:
>>>>> On Mon, 31 Jan 2022 13:31:11 +0000, Roland Perry
>>>>><roland@perry.co.uk> wrote:
>>>>>
>>>>>> In message <st8l2g$8md$1@dont-email.me>, at 12:35:28 on Mon, 31 Jan
>>>>>> 2022, Recliner <recliner.usenet@gmail.com> remarked:
>>>>>>> Graham Harrison <edward.harrisom.one@btinternet.com> wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>>https://www.dailymail.co.uk/news/article-10457643/Train-driver-avoids-d
>>>>>>>>
>>>>>>>>erailment-leaving-cab-dangling-track-damaged-floodwater.html?ito=native
>>>>>>>> _share_article-masthead
>>>>>>>> I'm not a fan of the Daily Mail but ........
>>>>>>>
>>>>>>> https://twitter.com/ianhardie9018/status/1487783395660869633?s=21
>>>>>>
>>>>>> That shows a significantly bigger sideways displacement than the
>>>>>>earlier
>>>>>> photos. I wonder how much of that was "push" from the braking train (I
>>>>>> think the rogue water flow was the opposite direction).
>>>>>
>>>>> Yes, it does give the impression that it was derailed. I think the
>>>>> sagging track may have slewed towards the water, and
>>>>> the first bogie entered that section.
>>>>
>>>>
>>>> There was a suggestion on Twitter that the driver could have reversed,
>>>> but if I'd been the driver, I think that I'd have been very happy just
>>>> to get everybody off the train safely. Including myself!
>>>>
>>>
>>> Yes, you definitely wouldn't be moving that train without authority
>>>from NR
>>> and various people watching the affected bogie to make sure it didn't
>>> misbehave! And you also wouldn't be doing it without that
>>>authorisation etc
>>> because every action you take is recorded.
>>>
>>>
>>> Anna Noyd-Dryver
>>>
>>  Some real facts at last
>>https://www.gov.uk/government/news/train-running-onto-a-washed-out-sect
>>ion-of-line-near-haddiscoe
>
>Interesting that both ideas mentioned in this thread are neither supported.
>
>1. Most people have said that the line slid sideways due to the ballast
>washing away on one side before the other and before the train's
>arrival.

>2. Roland's view that the sideways must have been a result of the
>train's braking and that the track would have stayed straight without a
>train's arrival.
>
>The report quotes "Over the next twenty minutes the flowing water
>caused all support for the track to be lost and the track sank
>significantly, causing the front carriage to tilt forwards and sideways."
>
>This makes it clear that the sideways movement occurs after the train
>had stopped so neither 1 nor 2 above happened!

If you read back, what I was trying to achieve was dispelling the notion
that the sideways movement had happened before the train arrived (and
spotting it was what caused the driver to brake).

And also asked if anyone had "earlier" pictures, which they didn't. But
given the insistence that the sideways movement was at the very least
present by the time the train had stopped, all that left was it being
caused by the train.

I'm glad it's all sorted now, and that the most strident notions about
the track sliding down some sort of slope under its own weight, have
been well and truly debunked.
--
Roland Perry

Marland <gemehabal@btinternet.co.uk> wrote:
> Anna Noyd-Dryver <anna@noyd-dryver.com> wrote:
>> Roland Perry <roland@perry.co.uk> wrote:
>>> In message <suu39r$8l7$2@dont-email.me>, at 19:03:23 on Sun, 20 Feb
>>> 2022, Anna Noyd-Dryver <anna@noyd-dryver.com> remarked:
>>>> Roland Perry <roland@perry.co.uk> wrote:
>>>>> In message <sus5aj$fgn$2@dont-email.me>, at 01:25:39 on Sun, 20 Feb
>>>>> 2022, Anna Noyd-Dryver <anna@noyd-dryver.com> remarked:
>>>>>> Roland Perry <roland@perry.co.uk> wrote:
>>>>>>
>>>>>>>
>>>>>>> How fast was the train going, or do you have "no idea, really"?
>>>>>>>
>>>>>>> It's almost exactly 800m from the next station were it would stop, and
>>>>>>> the previous station is 4.5 miles away,
>>>
>>> Correction, between the stations is 4 miles.
>>>
>>>>>>> transit time 9mins, so that's an average of 30mph (yes the cruising
>>>>>>> speed will be more, but not vastly so).
>>>>>>
>>>>>> From the clues available in the picture (white house, trackside hut) and
>>>>>> also what's not visible (two pylons behind the photographer), the location
>>>>>> is around halfway along the straight alongside the Haddiscoe Cut <Dropped
>>>>>> pin
>>>>>> https://goo.gl/maps/Ba6QPUDY4wF3LgpA8>
>>>>>
>>>>> You don't think it's the hut 260m north-east of the bridge (which would
>>>>> be a handy place to take the photos from)?
>>>>>
>>>>> There's also this bunker in shot:
>>>>>
>>>>> <https://i.dailymail.co.uk/1s/2022/01/30/18/53556259-10457643-image-a-29
>>>>> _1643569181496.jpg>
>>>>>
>>>>> So: https://goo.gl/maps/HLxC82rRBqFT17iY7
>>>>
>>>> Yes I think you're right; the white building in shot is further from the
>>>> line than the one I identified on the map.
>>>>
>>>> Still around 1km from the station, could easily still be running at
>>>> 50-60mph, though I don't know local habits.
>>>
>>> Maybe we can look at the timetable again.
>>>
>>> If it's 20mph as far as the Reedham swing bridge, that's 1.5km (sorry
>>> about the mixed units) and hence a little under a mile, so maybe three
>>> minutes. Then it's 2.5 miles to the site, plus half a mile to the next
>>> station.
>>>
>>> If we take a minute off the timetabled 9mins to account for station
>>> dwell time, that leaves five minutes do the three miles from swing
>>> bridge to station. Average of 36mph I think.
>>>
>>
>> I very much think that the train speed would get up to 60mph in the three
>> miles between the swing bridge and the station. Reference: I get up to
>> 65-70mph between two stops which are 2.5 miles apart, and I suspect that
>> FLIRTs accelerate faster.
>>
>>> Given you are leaning towards quite late braking for such a station, I
>>> don't think the cruising speed will be much above 40mph. Unless it
>>> always dwells at the stations for longer than the timetable suggests.
>>>
>>
>> I don't consider 50-60mph at 1km from the station to be particularly late
>> braking; it's the standard approach to Port Talbot in both directions, for
>> example (using that example because approach speed is around 60mph (having
>> coasted a little from the 70mph linespeed) and the braking point is easily
>> identifiable on Google maps).
>>
>> It may be that local practice is to already be braking for the station by
>> the location of the incident, in which case speed may have been around
>> 50mph or so.
>>
>>>>>> Linespeed is 20mph across Reedham swing bridge then 60 mph through the
>>>>>> non-derailment site and Haddiscoe station then drops to 30mph for
>>>>>> Somerleyton swing bridge.
>>>>>>
>>>>>> It’s around 2.5 miles between the speed increase and the station, so I'd
>>>>>> fully expect the train to reach 60mph. Around 1.5 miles from the station, I
>>>>>> don't think the driver would be braking yet.
>>>>>
>>>>> Meanwhile, on the more general point about rail tension, droop, and
>>>>> sideways displacement, the other track here is showing very little
>>>>> displacement in *any* direction:
>>>>>
>>>>> <https://i.dailymail.co.uk/1s/2022/01/30/18/53556263-10457643-image-m-23
>>>>> _1643568862268.jpg?
>>>>>
>>>>> The track the train is on, is drooping because of the weight of the
>>>>> front bogie.
>>>>>
>>>>> And four sleepers ahead of the front of the train is a rail joint, so
>>>>> maybe it wasn't quite as tensioned as earlier thought (but still
>>>>> tensioned enough not to veer off sideways, I think).
>>>>
>>>> Good spot, it's jointed bullhead rail so no (intentional!) tension at all.
>>>
>>> How much does such a joint expand and contract normally? We know it was
>>> cold, so could be towards the "shrinking" end of its play. And then the
>>> droop will pull the joint even further apart.
>>>
>>
>> Around 1/4"-1/2" per joint, OTTOMH.
>>
>>> The infamous zigzag pictured in only one of the media, would also be
>>> facilitated by the braking of the train pulling the joint(s) beneath the
>>> train (about one per carriage-length I think, but perhaps someone can
>>> confirm) a bit further apart than normal, and pushing the one just ahead
>>> of the train perhaps into compression.
>>
>> I know bullhead rail isn't held as tightly to the sleepers as flat-bottomed
>> rail, especially with wooden keys; but I'd be very surprised if emergency
>> braking of a one train would move it longitudinally sufficiently to alter
>> the rail joint gaps.
>>
>>
>> Anna Noyd-Dryver
>>
>
> Keys in Bullhead track where there are double or tracks are inserted on the
> side of the chair that is facing the normal direction of approach, this is
> done so any forces caused by braking that may produce rail creep will pull
> the keys into the chair and grip the rail tighter ,though the keys are not
> wedge shaped the general friction caused by rust and muck makes them behave
> that way.
>
> ISTR that jointed bullhead isn’t under any tension , wasn’t it one of the
> jobs of PW staff to keep the fishplate bolts lubricated enough the movement
> of a rail due to temperature changes just opened and closed the gaps with
> not effect on the joining rail. However you would not want rails so loose
> in the chairs that forces from the train wheels either from propulsion or
> braking is sliding the rails forward and back. You would end up with quite
> noisy track as the rails butted up on adjacent ones as gaps closed up at
> one end or the other and the wear on fishplate blots would shorten their
> life.

The Tattenhall rail crash in 1971 was caused because jointed rails had
crept and were butting up against each other, and in the hot weather
expansion caused the track to buckle under a passing train. The PW staff
were aware and were planning to shift the rails back so the rail gaps were
even.

https://www.railwaysarchive.co.uk/docsummary.php?docID=277

Sam

--
The entity formerly known as Sam.Wilson@ed.ac.uk
Spit the dummy to reply

Roland Perry <roland@perry.co.uk> wrote:
> In message <sv2ncj$uh7$1@dont-email.me>, at 13:10:45 on Tue, 22 Feb
> 2022, ColinR <rail@greystane.shetland.co.uk> remarked:
>> On 22/02/2022 11:17, ianb wrote:
>>> On 01/02/2022 14:20, Anna Noyd-Dryver wrote:
>>>> GB <NOTsomeone@microsoft.invalid> wrote:
>>>>> On 31/01/2022 13:43, Recliner wrote:
>>>>>> On Mon, 31 Jan 2022 13:31:11 +0000, Roland Perry
>>>>>> <roland@perry.co.uk> wrote:
>>>>>>
>>>>>>> In message <st8l2g$8md$1@dont-email.me>, at 12:35:28 on Mon, 31 Jan
>>>>>>> 2022, Recliner <recliner.usenet@gmail.com> remarked:
>>>>>>>> Graham Harrison <edward.harrisom.one@btinternet.com> wrote:
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> https://www.dailymail.co.uk/news/article-10457643/Train-driver-avoids-d
>>>>>>>>>
>>>>>>>>> erailment-leaving-cab-dangling-track-damaged-floodwater.html?ito=native
>>>>>>>>> _share_article-masthead
>>>>>>>>> I'm not a fan of the Daily Mail but ........
>>>>>>>>
>>>>>>>> https://twitter.com/ianhardie9018/status/1487783395660869633?s=21
>>>>>>>
>>>>>>> That shows a significantly bigger sideways displacement than the
>>>>>>> earlier
>>>>>>> photos. I wonder how much of that was "push" from the braking train (I
>>>>>>> think the rogue water flow was the opposite direction).
>>>>>>
>>>>>> Yes, it does give the impression that it was derailed. I think the
>>>>>> sagging track may have slewed towards the water, and
>>>>>> the first bogie entered that section.
>>>>>
>>>>>
>>>>> There was a suggestion on Twitter that the driver could have reversed,
>>>>> but if I'd been the driver, I think that I'd have been very happy just
>>>>> to get everybody off the train safely. Including myself!
>>>>>
>>>>
>>>> Yes, you definitely wouldn't be moving that train without authority
>>>> from NR
>>>> and various people watching the affected bogie to make sure it didn't
>>>> misbehave! And you also wouldn't be doing it without that
>>>> authorisation etc
>>>> because every action you take is recorded.
>>>>
>>>>
>>>> Anna Noyd-Dryver
>>>>
>>>  Some real facts at last
>>> https://www.gov.uk/government/news/train-running-onto-a-washed-out-sect
>>> ion-of-line-near-haddiscoe
>>
>> Interesting that both ideas mentioned in this thread are neither supported.
>>
>> 1. Most people have said that the line slid sideways due to the ballast
>> washing away on one side before the other and before the train's
>> arrival.
>
>> 2. Roland's view that the sideways must have been a result of the
>> train's braking and that the track would have stayed straight without a
>> train's arrival.
>>
>> The report quotes "Over the next twenty minutes the flowing water
>> caused all support for the track to be lost and the track sank
>> significantly, causing the front carriage to tilt forwards and sideways."
>>
>> This makes it clear that the sideways movement occurs after the train
>> had stopped so neither 1 nor 2 above happened!
>
> If you read back, what I was trying to achieve was dispelling the notion
> that the sideways movement had happened before the train arrived (and
> spotting it was what caused the driver to brake).
>
> And also asked if anyone had "earlier" pictures, which they didn't. But
> given the insistence that the sideways movement was at the very least
> present by the time the train had stopped, all that left was it being
> caused by the train.
>
> I'm glad it's all sorted now, and that the most strident notions about
> the track sliding down some sort of slope under its own weight, have
> been well and truly debunked.

Yes, it turns out we were all wrong. Your most strident assertion, that
the track must have remained straight because it was under tension, has
also been completely debunked in a different subthread because the jointed
track was not under tension. A little humility would make life here much
more pleasant.

Sam

--
The entity formerly known as Sam.Wilson@ed.ac.uk
Spit the dummy to reply

In message <svdjpv$e1j$1@dont-email.me>, at 16:17:03 on Sat, 26 Feb
2022, Sam Wilson <ukr@dummy.wislons.fastmail.co.uk> remarked:

>> I'm glad it's all sorted now, and that the most strident notions about
>> the track sliding down some sort of slope under its own weight, have
>> been well and truly debunked.
>
>Yes, it turns out we were all wrong. Your most strident assertion, that
>the track must have remained straight because it was under tension, has
>also been completely debunked in a different subthread because the jointed
>track was not under tension. A little humility would make life here much
>more pleasant.

You are misdirecting yourself. While I agree that whoever implied it was
continuously-welded rail under tension (an assertion upon which much
later speculation was based) was mistaken, even classic jointed rail has
very limited "stretch" built into it.

But even *that* turns out to be a red herring because the track didn't
slide sideways "down a slope", because the driver is now known to have
just seen a dip.

And all the photos purporting to show otherwise are now known to be
hours later *after* the ground had eroded even more.

The prior zig-zag is a hoax, and that's all I was trying to say.
--
Roland Perry

On 26/02/2022 17:21, Roland Perry wrote:
> In message <svdjpv$e1j$1@dont-email.me>, at 16:17:03 on Sat, 26 Feb
> 2022, Sam Wilson <ukr@dummy.wislons.fastmail.co.uk> remarked:
>
>>> I'm glad it's all sorted now, and that the most strident notions about
>>> the track sliding down some sort of slope under its own weight, have
>>> been well and truly debunked.
>>
>> Yes, it turns out we were all wrong.  Your most strident assertion, that
>> the track must have remained straight because it was under tension, has
>> also been completely debunked in a different subthread because the
>> jointed
>> track was not under tension.  A little humility would make life here much
>> more pleasant.
>
> You are misdirecting yourself. While I agree that whoever implied it was
> continuously-welded rail under tension (an assertion upon which much
> later speculation was based) was mistaken, even classic jointed rail has
> very limited "stretch" built into it.
>
> But even *that* turns out to be a red herring because the track didn't
> slide sideways "down a slope", because the driver is now known to have
> just seen a dip.
>
> And all the photos purporting to show otherwise are now known to be
> hours later *after* the ground had eroded even more.
>
> The prior zig-zag is a hoax, and that's all I was trying to say.

And that folks, is called "humility".....

--
Colin

In message <sve0ia$7mn$1@dont-email.me>, at 19:54:53 on Sat, 26 Feb
2022, ColinR <rail@greystane.shetland.co.uk> remarked:
>On 26/02/2022 17:21, Roland Perry wrote:
>> In message <svdjpv$e1j$1@dont-email.me>, at 16:17:03 on Sat, 26 Feb
>>2022, Sam Wilson <ukr@dummy.wislons.fastmail.co.uk> remarked:
>>
>>>> I'm glad it's all sorted now, and that the most strident notions
>>>>about the track sliding down some sort of slope under its own
>>>>weight, have been well and truly debunked.
>>>
>>> Yes, it turns out we were all wrong.  Your most strident assertion,
>>>that the track must have remained straight because it was under
>>>tension, has also been completely debunked in a different subthread
>>>because the jointed track was not under tension.  A little humility
>>>would make life here much more pleasant.

>> You are misdirecting yourself. While I agree that whoever implied it
>>was continuously-welded rail under tension (an assertion upon which
>>much later speculation was based) was mistaken, even classic jointed
>>rail has very limited "stretch" built into it.

>> But even *that* turns out to be a red herring because the track
>>didn't slide sideways "down a slope", because the driver is now known
>>to have just seen a dip.

>> And all the photos purporting to show otherwise are now known to be
>>hours later *after* the ground had eroded even more.

>> The prior zig-zag is a hoax, and that's all I was trying to say.
>
>And that folks, is called "humility".....

We maybe need some humility from whoever posted that it was continuous
welded rail, which none of us (not even I) challenged.

The main humility required here is those who stridently insisted the
track had slid sideways/downhill, when that's been completely debunked.

I'm afraid I'm not going to apologise for sticking to my guns that the
sideways/downhill theory was nonsense.
--
Roland Perry

ColinR <rail@greystane.shetland.co.uk> wrote:
> On 26/02/2022 17:21, Roland Perry wrote:
>> In message <svdjpv$e1j$1@dont-email.me>, at 16:17:03 on Sat, 26 Feb
>> 2022, Sam Wilson <ukr@dummy.wislons.fastmail.co.uk> remarked:
>>
>>>> I'm glad it's all sorted now, and that the most strident notions about
>>>> the track sliding down some sort of slope under its own weight, have
>>>> been well and truly debunked.
>>>
>>> Yes, it turns out we were all wrong.  Your most strident assertion, that
>>> the track must have remained straight because it was under tension, has
>>> also been completely debunked in a different subthread because the
>>> jointed
>>> track was not under tension.  A little humility would make life here much
>>> more pleasant.
>>
>> You are misdirecting yourself. While I agree that whoever implied it was
>> continuously-welded rail under tension (an assertion upon which much
>> later speculation was based) was mistaken, even classic jointed rail has
>> very limited "stretch" built into it.
>>
>> But even *that* turns out to be a red herring because the track didn't
>> slide sideways "down a slope", because the driver is now known to have
>> just seen a dip.
>>
>> And all the photos purporting to show otherwise are now known to be
>> hours later *after* the ground had eroded even more.
>>
>> The prior zig-zag is a hoax, and that's all I was trying to say.
>
>
> And that folks, is called "humility".....
>

Indeed. As Roland has never been wrong about anything, ever, he has nothing
to be humble about.

In message <svg8gp$3r1$1@dont-email.me>, at 16:22:49 on Sun, 27 Feb
2022, Recliner <recliner.usenet@gmail.com> remarked:
>ColinR <rail@greystane.shetland.co.uk> wrote:
>> On 26/02/2022 17:21, Roland Perry wrote:
>>> In message <svdjpv$e1j$1@dont-email.me>, at 16:17:03 on Sat, 26 Feb
>>> 2022, Sam Wilson <ukr@dummy.wislons.fastmail.co.uk> remarked:
>>>
>>>>> I'm glad it's all sorted now, and that the most strident notions about
>>>>> the track sliding down some sort of slope under its own weight, have
>>>>> been well and truly debunked.
>>>>
>>>> Yes, it turns out we were all wrong.  Your most strident assertion, that
>>>> the track must have remained straight because it was under tension, has
>>>> also been completely debunked in a different subthread because the
>>>> jointed
>>>> track was not under tension.  A little humility would make life here much
>>>> more pleasant.
>>>
>>> You are misdirecting yourself. While I agree that whoever implied it was
>>> continuously-welded rail under tension (an assertion upon which much
>>> later speculation was based) was mistaken, even classic jointed rail has
>>> very limited "stretch" built into it.
>>>
>>> But even *that* turns out to be a red herring because the track didn't
>>> slide sideways "down a slope", because the driver is now known to have
>>> just seen a dip.
>>>
>>> And all the photos purporting to show otherwise are now known to be
>>> hours later *after* the ground had eroded even more.
>>>
>>> The prior zig-zag is a hoax, and that's all I was trying to say.
>>
>> And that folks, is called "humility".....
>
>Indeed. As Roland has never been wrong about anything, ever, he has nothing
>to be humble about.

That playbook comes out again.

Yes, there are several things I've not got right, but this episode with
the sideways sliding track isn't one of them. Modulo I was probably
wrong to assume the person who originally mentioned continuous welded
rail tension at that site was correct.

Oh, that was you! (I wasn't going to mention it, but you've forced my
hand).
--
Roland Perry

Roland Perry <roland@perry.co.uk> wrote:
> In message <svg8gp$3r1$1@dont-email.me>, at 16:22:49 on Sun, 27 Feb
> 2022, Recliner <recliner.usenet@gmail.com> remarked:
>> ColinR <rail@greystane.shetland.co.uk> wrote:
>>> On 26/02/2022 17:21, Roland Perry wrote:
>>>> In message <svdjpv$e1j$1@dont-email.me>, at 16:17:03 on Sat, 26 Feb
>>>> 2022, Sam Wilson <ukr@dummy.wislons.fastmail.co.uk> remarked:
>>>>
>>>>>> I'm glad it's all sorted now, and that the most strident notions about
>>>>>> the track sliding down some sort of slope under its own weight, have
>>>>>> been well and truly debunked.
>>>>>
>>>>> Yes, it turns out we were all wrong.  Your most strident assertion, that
>>>>> the track must have remained straight because it was under tension, has
>>>>> also been completely debunked in a different subthread because the
>>>>> jointed
>>>>> track was not under tension.  A little humility would make life here much
>>>>> more pleasant.
>>>>
>>>> You are misdirecting yourself. While I agree that whoever implied it was
>>>> continuously-welded rail under tension (an assertion upon which much
>>>> later speculation was based) was mistaken, even classic jointed rail has
>>>> very limited "stretch" built into it.
>>>>
>>>> But even *that* turns out to be a red herring because the track didn't
>>>> slide sideways "down a slope", because the driver is now known to have
>>>> just seen a dip.
>>>>
>>>> And all the photos purporting to show otherwise are now known to be
>>>> hours later *after* the ground had eroded even more.
>>>>
>>>> The prior zig-zag is a hoax, and that's all I was trying to say.
>>>
>>> And that folks, is called "humility".....
>>
>> Indeed. As Roland has never been wrong about anything, ever, he has nothing
>> to be humble about.
>
> That playbook comes out again.
>
> Yes, there are several things I've not got right, but this episode with
> the sideways sliding track isn't one of them. Modulo I was probably
> wrong to assume the person who originally mentioned continuous welded
> rail tension at that site was correct.
>
> Oh, that was you! (I wasn't going to mention it, but you've forced my
> hand).

You were delighted to assume, just as I did, that it was CWR when you
thought it supported your theory (which turned out to be no more correct
than any others that were proposed):

Roland Perry <roland@perry.co.uk> wrote:
> In message <stoe9d$fkg$1@dont-email.me>, at 12:17:49 on Sun, 6 Feb 2022,
> Recliner <recliner.usenet@gmail.com> remarked:
>> Roland Perry <roland@perry.co.uk> wrote:
>>> In message <sto9hd$g9t$1@dont-email.me>, at 10:56:45 on Sun, 6 Feb 2022,
>>> Recliner <recliner.usenet@gmail.com> remarked:
>>>> Roland Perry <roland@perry.co.uk> wrote:
>>>>> In message <sto7bj$5cb$2@dont-email.me>, at 10:19:31 on Sun, 6 Feb 2022,
>>>>> Anna Noyd-Dryver <anna@noyd-dryver.com> remarked:
>>>>>> Roland Perry <roland@perry.co.uk> wrote:
>>>>>>> In message <sth7uq$f0i$1@dont-email.me>, at 18:46:50 on Thu, 3 Feb 2022,
>>>>>>> Tweed <usenet.tweed@gmail.com> remarked:
>>>>>>>> Anna Noyd-Dryver <anna@noyd-dryver.com> wrote:
>>>>>>>>> Roland Perry <roland@perry.co.uk> wrote:
>>>>>>>>>> In message <stgal4$t5h$1@dont-email.me>, at 10:26:45 on Thu, 3
>>>>>>>>>> Feb 2022,
>>>>>>>>>> Anna Noyd-Dryver <anna@noyd-dryver.com> remarked:
>>>>>>>>>>
>>>>>>>>>>>>> If you watch a stream of water cutting a channel, it’s
>>>>>>>>>>>>>
>>>>>>>>>>>>> upstream end of the channel that gets the most energetic erosion.
>>>>>>>>>>>>
>>>>>>>>>>>> Yes, but why does that cause lateral slewing (upstream), rather than
>>>>>>>>>>>> more droop?
>>>>>>>>>>>
>>>>>>>>>>> Because the upstream side of the track gets eroded-under first,
>>>>>>>>>>> before the other side of the track. So the track is unsupported
>>>>>>>>>>> under one side only; has non-zero weight and is not a rigid
>>>>>>>>>>> structure. Why do you think it *wouldn't* slew to one side?
>>>>>>>>>>> It's not Hornby "long straight" rigid track which can be used
>>>>>>>>>>> as a bridge without any further support!
>>>>>>>>>>
>>>>>>>>>> Slewing requires a horizontal force perpendicular to the
>>>>>>>>>> track, and what
>>>>>>>>>> is providing that force. Drooping requires gravity acting
>>>>>>>>>> downwards, and
>>>>>>>>>> that's in plentiful supply.
>>>>>>>>>
>>>>>>>>> The imbalance of force is provided by the erosion being initially
>>>>>>>>> predominantly under one side only of the track.
>>>>>>>>
>>>>>>>> If you put a marble on a slope the only force according to
>>>>>>>> Roland is just downwards gravity. Yet as the marble rolls down
>>>>>>>> the hill it moves both vertically and horizontally.
>>>>>>>>
>>>>>>>> The eroded track length is effectively rolling down hill (well
>>>>>>>> not rolling but you know what I mean).
>>>>>>>
>>>>>>> If the ground under the track has eroded by more than about six inches,
>>>>>>> there isn't a slope for the track to slide down. It's just hanging in
>>>>>>> mid air.
>>>>>>
>>>>>> But at that point it had only eroded under *one side of the track*.
>>>>>
>>>>> Sure about that?
>>>>>
>>>>> <https://i.dailymail.co.uk/1s/2022/01/30/18/53556263-10457643-image-m-
>>>>> 23_1643568862268.jpg>
>>>>
>>>> That was taken later.
>>>
>>> What we need (and there won't be one, unless GA released some cab
>>> footage) is a picture of the tracks before the train arrived.
>>>
>>> The one linked above doesn't show anything like as much of a kink as
>>> <https://twitter.com/ianhardie9018/status/1487783395660869633?s=21>
>>> which suggests it was moving left and right quite a bit.
>>>
>>> I still think the ianhardie kink is a result of the track buckling from
>>> the braking force of the train, not sliding sideways downhill.
>>
>> Why would braking cause a track to buckle sideways? CWR is under tension.
>
> If it's under tension [and yes, I agree it is, and underpins my own
> theory], how can it do a crazy zig-zag buckle in the way that's being
> claimed, when the only force on it is gravity downwards - and what that
> would cause is just a small droop.

Recliner <recliner.usenet@gmail.com> wrote:
> Roland Perry <roland@perry.co.uk> wrote:
>> In message <svg8gp$3r1$1@dont-email.me>, at 16:22:49 on Sun, 27 Feb
>> 2022, Recliner <recliner.usenet@gmail.com> remarked:
>>> ColinR <rail@greystane.shetland.co.uk> wrote:
>>>> On 26/02/2022 17:21, Roland Perry wrote:
>>>>> In message <svdjpv$e1j$1@dont-email.me>, at 16:17:03 on Sat, 26 Feb
>>>>> 2022, Sam Wilson <ukr@dummy.wislons.fastmail.co.uk> remarked:
>>>>>
>>>>>>> I'm glad it's all sorted now, and that the most strident notions about
>>>>>>> the track sliding down some sort of slope under its own weight, have
>>>>>>> been well and truly debunked.
>>>>>>
>>>>>> Yes, it turns out we were all wrong.  Your most strident assertion, that
>>>>>> the track must have remained straight because it was under tension, has
>>>>>> also been completely debunked in a different subthread because the
>>>>>> jointed
>>>>>> track was not under tension.  A little humility would make life here much
>>>>>> more pleasant.
>>>>>
>>>>> You are misdirecting yourself. While I agree that whoever implied it was
>>>>> continuously-welded rail under tension (an assertion upon which much
>>>>> later speculation was based) was mistaken, even classic jointed rail has
>>>>> very limited "stretch" built into it.
>>>>>
>>>>> But even *that* turns out to be a red herring because the track didn't
>>>>> slide sideways "down a slope", because the driver is now known to have
>>>>> just seen a dip.
>>>>>
>>>>> And all the photos purporting to show otherwise are now known to be
>>>>> hours later *after* the ground had eroded even more.
>>>>>
>>>>> The prior zig-zag is a hoax, and that's all I was trying to say.
>>>>
>>>> And that folks, is called "humility".....
>>>
>>> Indeed. As Roland has never been wrong about anything, ever, he has nothing
>>> to be humble about.
>>
>> That playbook comes out again.
>>
>> Yes, there are several things I've not got right, but this episode with
>> the sideways sliding track isn't one of them. Modulo I was probably
>> wrong to assume the person who originally mentioned continuous welded
>> rail tension at that site was correct.
>>
>> Oh, that was you! (I wasn't going to mention it, but you've forced my
>> hand).
>
> You were delighted to assume, just as I did, that it was CWR when you
> thought it supported your theory (which turned out to be no more correct
> than any others that were proposed):
>
> Roland Perry <roland@perry.co.uk> wrote:
>> In message <stoe9d$fkg$1@dont-email.me>, at 12:17:49 on Sun, 6 Feb 2022,
>> Recliner <recliner.usenet@gmail.com> remarked:
>>> Roland Perry <roland@perry.co.uk> wrote:
>>>> In message <sto9hd$g9t$1@dont-email.me>, at 10:56:45 on Sun, 6 Feb 2022,
>>>> Recliner <recliner.usenet@gmail.com> remarked:
>>>>> Roland Perry <roland@perry.co.uk> wrote:
>>>>>> In message <sto7bj$5cb$2@dont-email.me>, at 10:19:31 on Sun, 6 Feb 2022,
>>>>>> Anna Noyd-Dryver <anna@noyd-dryver.com> remarked:
>>>>>>> Roland Perry <roland@perry.co.uk> wrote:
>>>>>>>> In message <sth7uq$f0i$1@dont-email.me>, at 18:46:50 on Thu, 3 Feb 2022,
>>>>>>>> Tweed <usenet.tweed@gmail.com> remarked:
>>>>>>>>> Anna Noyd-Dryver <anna@noyd-dryver.com> wrote:
>>>>>>>>>> Roland Perry <roland@perry.co.uk> wrote:
>>>>>>>>>>> In message <stgal4$t5h$1@dont-email.me>, at 10:26:45 on Thu, 3
>>>>>>>>>>> Feb 2022,
>>>>>>>>>>> Anna Noyd-Dryver <anna@noyd-dryver.com> remarked:
>>>>>>>>>>>
>>>>>>>>>>>>>> If you watch a stream of water cutting a channel, it’s
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> upstream end of the channel that gets the most energetic erosion.
>>>>>>>>>>>>>
>>>>>>>>>>>>> Yes, but why does that cause lateral slewing (upstream), rather than
>>>>>>>>>>>>> more droop?
>>>>>>>>>>>>
>>>>>>>>>>>> Because the upstream side of the track gets eroded-under first,
>>>>>>>>>>>> before the other side of the track. So the track is unsupported
>>>>>>>>>>>> under one side only; has non-zero weight and is not a rigid
>>>>>>>>>>>> structure. Why do you think it *wouldn't* slew to one side?
>>>>>>>>>>>> It's not Hornby "long straight" rigid track which can be used
>>>>>>>>>>>> as a bridge without any further support!
>>>>>>>>>>>
>>>>>>>>>>> Slewing requires a horizontal force perpendicular to the
>>>>>>>>>>> track, and what
>>>>>>>>>>> is providing that force. Drooping requires gravity acting
>>>>>>>>>>> downwards, and
>>>>>>>>>>> that's in plentiful supply.
>>>>>>>>>>
>>>>>>>>>> The imbalance of force is provided by the erosion being initially
>>>>>>>>>> predominantly under one side only of the track.
>>>>>>>>>
>>>>>>>>> If you put a marble on a slope the only force according to
>>>>>>>>> Roland is just downwards gravity. Yet as the marble rolls down
>>>>>>>>> the hill it moves both vertically and horizontally.
>>>>>>>>>
>>>>>>>>> The eroded track length is effectively rolling down hill (well
>>>>>>>>> not rolling but you know what I mean).
>>>>>>>>
>>>>>>>> If the ground under the track has eroded by more than about six inches,
>>>>>>>> there isn't a slope for the track to slide down. It's just hanging in
>>>>>>>> mid air.
>>>>>>>
>>>>>>> But at that point it had only eroded under *one side of the track*.
>>>>>>
>>>>>> Sure about that?
>>>>>>
>>>>>> <https://i.dailymail.co.uk/1s/2022/01/30/18/53556263-10457643-image-m-
>>>>>> 23_1643568862268.jpg>
>>>>>
>>>>> That was taken later.
>>>>
>>>> What we need (and there won't be one, unless GA released some cab
>>>> footage) is a picture of the tracks before the train arrived.
>>>>
>>>> The one linked above doesn't show anything like as much of a kink as
>>>> <https://twitter.com/ianhardie9018/status/1487783395660869633?s=21>
>>>> which suggests it was moving left and right quite a bit.
>>>>
>>>> I still think the ianhardie kink is a result of the track buckling from
>>>> the braking force of the train, not sliding sideways downhill.
>>>
>>> Why would braking cause a track to buckle sideways? CWR is under tension.
>>
>> If it's under tension [and yes, I agree it is, and underpins my own
>> theory], how can it do a crazy zig-zag buckle in the way that's being
>> claimed, when the only force on it is gravity downwards - and what that
>> would cause is just a small droop.
>
>
>
From the RAIB report

As the train approached the section of track concerned, the driver of the
train noticed what appeared to be standing water on the line ahead and
started braking. The train, which was formed of three passenger vehicles
and a power car, stopped with its front carriage above the flowing water.
Over the next twenty minutes the flowing water caused all support for the
track to be lost and the track sank significantly, causing the front
carriage to tilt forwards and sideways. The driver attempted to move the
train back clear of the damaged section of track, but this proved
impossible because of the angle of the front carriage.