Don't know if this has already been posted:

https://www.dailymail.co.uk/news/art...nched-commuter
-train-going-wrong-way-London-Tube-line-nearly-crashes.html

How on earth can this happen? Surely the chiltern driver knew what side of the
line he was on? And why didn't the tripcocks work or have they been removed
from that section of line now?

wrote:

No, I don't think ut has been posted.

Don't know if this has already been posted:

https://www.dailymail.co.uk/news/art...nched-commuter
-train-going-wrong-way-London-Tube-line-nearly-crashes.html

How on earth can this happen? Surely the chiltern driver knew what side of the
line he was on? And why didn't the tripcocks work or have they been removed
from that section of line now?

It looks like it was perhaps a track/points fault that took the Chiltern
train across a crossover towards the Chesham line. The driver duly stopped.

https://www.railnews.co.uk/news/2020/06/23-near-collision-at-chalfont-.html

THE RAIB is investigating a reported near-collision between a London
Underground train and a National Rail service on Sunday night.

An image from the scene shows a Chiltern Railways unit and a train of
Metropolitan Line S-Stock at a stand just a few metres apart at Chalfont &
Latimer, the junction for the Chesham branch.

Reports have claimed that the Chiltern train took the wrong route at a
crossover, taking it towards the Metropolitan unit, and other unconfirmed
reports say that the points and track were damaged.

Transport for London said: ‘We apologise to customers disrupted by the
closure of the Metropolitan line between Chalfont & Latimer and Chesham.
This is the result of an incident involving a Chiltern Railways train near
Chalfont & Latimer station. We are working with Chiltern Railways to
determine exactly what happened, and our engineers will repair the railway
to return it to service as quickly as possible.’

The Transport for London website was still reporting no service on the
Chesham branch on Tuesday afternoon, and attributing the suspension to a
‘track fault’.

Chiltern Railways said: ‘We have an excellent safety record and are working
with the Rail Accident Investigation Branch to understand the causes of
this incident.’

wrote:
On Wed, 24 Jun 2020 10:55:36 -0000 (UTC)
Recliner wrote:
wrote:

No, I don't think ut has been posted.

Don't know if this has already been posted:


https://www.dailymail.co.uk/news/art...unched-commute
r
-train-going-wrong-way-London-Tube-line-nearly-crashes.html

How on earth can this happen? Surely the chiltern driver knew what side of
the
line he was on? And why didn't the tripcocks work or have they been removed
from that section of line now?

It looks like it was perhaps a track/points fault that took the Chiltern
train across a crossover towards the Chesham line. The driver duly stopped.

https://www.railnews.co.uk/news/2020/06/23-near-collision-at-chalfont-.html

THE RAIB is investigating a reported near-collision between a London
Underground train and a National Rail service on Sunday night.

An image from the scene shows a Chiltern Railways unit and a train of
Metropolitan Line S-Stock at a stand just a few metres apart at Chalfont &
Latimer, the junction for the Chesham branch.

Reports have claimed that the Chiltern train took the wrong route at a
crossover, taking it towards the Metropolitan unit, and other unconfirmed
reports say that the points and track were damaged.

By the train or before it went across?

A Chiltern train shouldn't have crossed over, so it was presumably a points
fault that took it on to the wrong line.

It couldn't have been going very fast or would have derailed.

The train would have just stopped at the station, so it would have been
moving slowly.

I think this is the crossover:
https://goo.gl/maps/wLHa4MiJ6j664dEv9


The Transport for London website was still reporting no service on the
Chesham branch on Tuesday afternoon, and attributing the suspension to a
‘track fault’.

Probably the most serious type of fault other than the rail collapsing. This
could have been seriously nasty.

Yes, if it had happened to a train that hadn't just stopped, there would
have been a head-on collision.

On Wed, 24 Jun 2020 11:42:19 -0000 (UTC)
Recliner wrote:
I think this is the crossover:
https://goo.gl/maps/wLHa4MiJ6j664dEv9

Looks like it. Seems to allow trains on the main line to reach the Chesham
branch. I suspect they'll be going back to a chesham shuttle service for a
while.

wrote:
On Wed, 24 Jun 2020 11:42:19 -0000 (UTC)
Recliner wrote:
I think this is the crossover:
https://goo.gl/maps/wLHa4MiJ6j664dEv9

Looks like it. Seems to allow trains on the main line to reach the Chesham
branch. I suspect they'll be going back to a chesham shuttle service for a
while.

They can't, at least not with S stock, as it's too long for the bay
platform. They'd have to borrow a half-length train from another line.

In any case, normal Chesham services now seem to have been restored.

In article , writes
Don't know if this has already been posted:

https://www.dailymail.co.uk/news/art...nched-commuter
-train-going-wrong-way-London-Tube-line-nearly-crashes.html

How on earth can this happen?

Possibilities based on what I can see:

(1) Met train is heading for Chesham, the points are therefore set to
cross over, and the Chiltern train SPADed.

(2) Previous train through the area was a Met train to Chesham, the
points haven't been moved since, and the Chiltern train SPADed.

(3) Either of (1) or (2) but a wrong-side signalling failure meant the
Chiltern train got a green signal.

(4) Either of (1) or (2) but the signaller authorized the Chiltern
driver to pass the signal at danger.

(5) Repeat of Farnley Junction: a wiring fault meant the normal and
reverse positions of a crossover were exchanged in the signalling.

(6) Repeat of Barnham: an earth fault meant the points moved as the
train approached them.

I'm sure there are more possibilities. We'll have to wait and see what
the RAIB have to say.

Surely the chiltern driver knew what side of the
line he was on?

The crossover is close to the station, IIRC, so he would have gone into
emergency braking as soon as he either saw the points facing the wrong
way or when he realized he was on the crossover. Don't forget trains
take some distance to stop.

--
Clive D.W. Feather

On Wed, 24 Jun 2020 16:54:45 +0100
"Clive D.W. Feather" wrote:
In article , writes
Don't know if this has already been posted:

https://www.dailymail.co.uk/news/art...aunched-commut
er
-train-going-wrong-way-London-Tube-line-nearly-crashes.html

How on earth can this happen?

Possibilities based on what I can see:

(1) Met train is heading for Chesham, the points are therefore set to
cross over, and the Chiltern train SPADed.

(2) Previous train through the area was a Met train to Chesham, the
points haven't been moved since, and the Chiltern train SPADed.

Does that part of the Met still have tripcocks and if so surely they would
have prevented these 2 possibilities?

wrote:
On Wed, 24 Jun 2020 16:54:45 +0100
"Clive D.W. Feather" wrote:
In article , writes
Don't know if this has already been posted:

https://www.dailymail.co.uk/news/art...aunched-commut
er
-train-going-wrong-way-London-Tube-line-nearly-crashes.html

How on earth can this happen?

Possibilities based on what I can see:

(1) Met train is heading for Chesham, the points are therefore set to
cross over, and the Chiltern train SPADed.

(2) Previous train through the area was a Met train to Chesham, the
points haven't been moved since, and the Chiltern train SPADed.

Does that part of the Met still have tripcocks and if so surely they would
have prevented these 2 possibilities?




Yes, it still has trip cocks. The new signalling hasn't got that far. So,
unlikely to be a SPaD.

Clive D.W. Feather wrote:
In article , writes
Don't know if this has already been posted:

https://www.dailymail.co.uk/news/art...nched-commuter
-train-going-wrong-way-London-Tube-line-nearly-crashes.html

How on earth can this happen?

Possibilities based on what I can see:

(1) Met train is heading for Chesham, the points are therefore set to
cross over, and the Chiltern train SPADed.

I think the Met train was eastbound, and the Chiltern train heading for
Amersham, but was wrongly put on the crossover to the eastbound line.
That's the route taken by Met trains to Chesham, and no Chiltern train
should normally go that way.


(2) Previous train through the area was a Met train to Chesham, the
points haven't been moved since, and the Chiltern train SPADed.

I doubt it. The tripcock would have stopped it, even if the Chiltern driver
went through a red light at low speed.


(3) Either of (1) or (2) but a wrong-side signalling failure meant the
Chiltern train got a green signal.

Yes, possibly, the Chiltern got a green signal that would take it across
the crossover. But that's at least two failures, as that route should never
be set for a Chiltern train, and the signal should have been at red even
for a Met train heading for the crossover, given that it took it straight
towards an eastbound Met train.


(4) Either of (1) or (2) but the signaller authorized the Chiltern
driver to pass the signal at danger.

Why would a signaller authorize a Chiltern train to take the route to
Chesham, regardless of the signal?


(5) Repeat of Farnley Junction: a wiring fault meant the normal and
reverse positions of a crossover were exchanged in the signalling.

Wouldn't such a permanent fault have shown up much earlier?


(6) Repeat of Barnham: an earth fault meant the points moved as the
train approached them.

That sounds more likely. It's probably why the Chesham branch stayed closed
for a couple of days, while the points and all the wiring was carefully
checked.


I'm sure there are more possibilities. We'll have to wait and see what
the RAIB have to say.

Surely the chiltern driver knew what side of the
line he was on?

The crossover is close to the station, IIRC, so he would have gone into
emergency braking as soon as he either saw the points facing the wrong
way or when he realized he was on the crossover. Don't forget trains
take some distance to stop.

Yes, and having just left the C&L station, the train wouldn't have been
travelling very fast.

Recliner wrote:
Clive D.W. Feather wrote:
In article , writes
Don't know if this has already been posted:

https://www.dailymail.co.uk/news/art...nched-commuter
-train-going-wrong-way-London-Tube-line-nearly-crashes.html

How on earth can this happen?

Possibilities based on what I can see:

(1) Met train is heading for Chesham, the points are therefore set to
cross over, and the Chiltern train SPADed.

Looking at more pics, I'm leaning more to this theory. The trains seem to
have almost met when the Met train was standing at the C&L platform, so it
must have been an eastbound Chiltern train meeting a westbound Met train,
probably heading for Chesham. So the Chiltern train must have run through
and damaged the trailing points set for the Chesham branch.

But why didn't the tripcocks stop it well before then? Was it a signalling
fault, rather than a SPaD?



I think the Met train was eastbound, and the Chiltern train heading for
Amersham, but was wrongly put on the crossover to the eastbound line.
That's the route taken by Met trains to Chesham, and no Chiltern train
should normally go that way.


(2) Previous train through the area was a Met train to Chesham, the
points haven't been moved since, and the Chiltern train SPADed.

I doubt it. The tripcock would have stopped it, even if the Chiltern driver
went through a red light at low speed.


(3) Either of (1) or (2) but a wrong-side signalling failure meant the
Chiltern train got a green signal.

Yes, possibly, the Chiltern got a green signal that would take it across
the crossover. But that's at least two failures, as that route should never
be set for a Chiltern train, and the signal should have been at red even
for a Met train heading for the crossover, given that it took it straight
towards an eastbound Met train.


(4) Either of (1) or (2) but the signaller authorized the Chiltern
driver to pass the signal at danger.

Why would a signaller authorize a Chiltern train to take the route to
Chesham, regardless of the signal?


(5) Repeat of Farnley Junction: a wiring fault meant the normal and
reverse positions of a crossover were exchanged in the signalling.

Wouldn't such a permanent fault have shown up much earlier?


(6) Repeat of Barnham: an earth fault meant the points moved as the
train approached them.

That sounds more likely. It's probably why the Chesham branch stayed closed
for a couple of days, while the points and all the wiring was carefully
checked.


I'm sure there are more possibilities. We'll have to wait and see what
the RAIB have to say.

Surely the chiltern driver knew what side of the
line he was on?

The crossover is close to the station, IIRC, so he would have gone into
emergency braking as soon as he either saw the points facing the wrong
way or when he realized he was on the crossover. Don't forget trains
take some distance to stop.

Yes, and having just left the C&L station, the train wouldn't have been
travelling very fast.