" wrote:
On 24.04.15 12:42, Recliner wrote:
On Fri, 24 Apr 2015 10:48:01 +0000 (UTC),
d wrote:

On Fri, 24 Apr 2015 05:35:32 -0500
wrote:
In article , d
() wrote:

On Fri, 24 Apr 2015 08:36:52 +0000 (UTC)
Recliner wrote:
Given the tight curves and so on of the DLR system it might actually be
quite difficult to detect something at or exceeding your stopping
distance which is obstructing the tracks or even harder the bits
between or at the side of the tracks.

Presumably the only places you'd fit it is where people routinely get
near the tracks: stations. The detectors would be fitted in front of the
platforms (which are straight) and could stop a train coming into the
station if someone or something had fallen from a platform on to the
tracks. Aren't remotely monitored level crossings already fitted with
similar devices?

I'm surprised the RMT haven't picked up on this with an I-told-you-so
tagline. If they did they'd have a point. The DLR is a damn sight busier
than it was ever envisiged to be and I'm not convinced that not having the
train operator at the front is a good idea any more.

How many incidents have there been?

How many do their need to be? I think the DLR are lucky that for some reason
suiciders seem to prefer the tube or NR for their finale.

Perhaps I can refer you to what you said of the 2000 road deaths:

Around 2000 deaths pa

So what? That amount barely even registers in the total deaths in the UK
per annum which is about 500K. Also that amount has been dropping steadily
since the 70s despite the vast increase in the number of cars on our roads.

Anyway, guess what - life has risks. Get over it.

So you think 2000 road deaths 'barely even registers', but a single
DLR death is intolerable?

And if you think having a human driver would save lives on the DLR,
how come most of the rail fatalities happen with trains with human
drivers on the Tube and NR?

Aren't there detectors at stations that will either stop a train or cut
power in the event that somebody falls onto the tracks.

Apparently not.

Skytrain in Vancouver has such a system, AIUI.

Yes, the discussion was whether the DLR should have such a system, too. It
is indeed slightly surprising that it doesn't. Perhaps the fear is of false
positives (eg, when a bit of rubbish triggers the detector -- you can just
imagine the local yobs experimenting to see just what it took to stop the
trains).

On 25.04.15 15:49, Recliner wrote:
" wrote:
On 24.04.15 12:42, Recliner wrote:
On Fri, 24 Apr 2015 10:48:01 +0000 (UTC),
d wrote:

On Fri, 24 Apr 2015 05:35:32 -0500
wrote:
In article , d
() wrote:

On Fri, 24 Apr 2015 08:36:52 +0000 (UTC)
Recliner wrote:
Given the tight curves and so on of the DLR system it might actually be
quite difficult to detect something at or exceeding your stopping
distance which is obstructing the tracks or even harder the bits
between or at the side of the tracks.

Presumably the only places you'd fit it is where people routinely get
near the tracks: stations. The detectors would be fitted in front of the
platforms (which are straight) and could stop a train coming into the
station if someone or something had fallen from a platform on to the
tracks. Aren't remotely monitored level crossings already fitted with
similar devices?

I'm surprised the RMT haven't picked up on this with an I-told-you-so
tagline. If they did they'd have a point. The DLR is a damn sight busier
than it was ever envisiged to be and I'm not convinced that not having the
train operator at the front is a good idea any more.

How many incidents have there been?

How many do their need to be? I think the DLR are lucky that for some reason
suiciders seem to prefer the tube or NR for their finale.

Perhaps I can refer you to what you said of the 2000 road deaths:

Around 2000 deaths pa

So what? That amount barely even registers in the total deaths in the UK
per annum which is about 500K. Also that amount has been dropping steadily
since the 70s despite the vast increase in the number of cars on our roads.

Anyway, guess what - life has risks. Get over it.

So you think 2000 road deaths 'barely even registers', but a single
DLR death is intolerable?

And if you think having a human driver would save lives on the DLR,
how come most of the rail fatalities happen with trains with human
drivers on the Tube and NR?

Aren't there detectors at stations that will either stop a train or cut
power in the event that somebody falls onto the tracks.

Apparently not.

Skytrain in Vancouver has such a system, AIUI.

Yes, the discussion was whether the DLR should have such a system, too. It
is indeed slightly surprising that it doesn't. Perhaps the fear is of false
positives (eg, when a bit of rubbish triggers the detector -- you can just
imagine the local yobs experimenting to see just what it took to stop the
trains).

Would need to a certain size and mass in order to activate the triggers,
however. I'm sure that they could calibrate such a system.

In message ,
d wrote:
Except the person who was killed fell on the track by accident apparently
12 seconds before the train ran over her. Unless the driver was asleep he'd
have had no problem stopping the train in time.

Is that so? It's not obvious: a main line train takes 90 seconds to stop
from 100 mph at the braking rates the signalling is designed for.

A 3-unit DLR train is 84 metres long. The braking system is designed for
0.6 m/s^2, so that means the train will enter the platform at 10 m/s and
take 16.7 seconds to stop. 12 seconds before that the train is doing
17.2 m/s and is 162 metres from the start of the platform.

Suppose someone was at the entry end of the platform and fell at that
point, the driver takes 1 second to react, and the emergency braking
rate is 1.2 m/s^2, then after 1 second the train is 146 m from the
platform and at 16.6 m/s. It will then take 13.8 seconds to stop and
proceed another 115 m. So, yes, in that situation it will work.

I'll let you do the calculations for other places on the platform.

However, will the victim be visible at 162 metres from the platform?
Particularly if there's a curve on the track.

Unless you're claiming that no train with a driver has ever managed to make an
emergency stop before hitting something or someone on the track in the entire
history of railways, then I think you'll have to concede that having a pair
of eyes up front is probably a Good Thing.

Will it be worth the cost? How much will it cost to add a driver to
every DLR train? If I recall the previous posting, we're talking about
one accident every 5 years and one suicide a year.

--
Clive D.W. Feather | Home:
Mobile: +44 7973 377646 | Web: http://www.davros.org
Please reply to the Reply-To address, which is:

"Clive D. W. Feather" wrote:
In message , d wrote:
Except the person who was killed fell on the track by accident apparently
12 seconds before the train ran over her. Unless the driver was asleep he'd
have had no problem stopping the train in time.

Is that so? It's not obvious: a main line train takes 90 seconds to stop
from 100 mph at the braking rates the signalling is designed for.

A 3-unit DLR train is 84 metres long. The braking system is designed for
0.6 m/s^2, so that means the train will enter the platform at 10 m/s and
take 16.7 seconds to stop. 12 seconds before that the train is doing 17.2
m/s and is 162 metres from the start of the platform.

Suppose someone was at the entry end of the platform and fell at that
point, the driver takes 1 second to react, and the emergency braking rate
is 1.2 m/s^2, then after 1 second the train is 146 m from the platform
and at 16.6 m/s. It will then take 13.8 seconds to stop and proceed
another 115 m. So, yes, in that situation it will work.

I'll let you do the calculations for other places on the platform.

However, will the victim be visible at 162 metres from the platform?
Particularly if there's a curve on the track.

Unless you're claiming that no train with a driver has ever managed to make an
emergency stop before hitting something or someone on the track in the entire
history of railways, then I think you'll have to concede that having a pair
of eyes up front is probably a Good Thing.

Will it be worth the cost? How much will it cost to add a driver to every
DLR train? If I recall the previous posting, we're talking about one
accident every 5 years and one suicide a year.

I think the stats showed four probably accidental fatalities and six
successful suicides in 11 years. The latter would probably still happen
with or without alert drivers or obstruction detectors, if the would-be
suicides jumped just as the train entered the platform at speed. That means
that only about one accidental death every three years might be saved, and
that's assuming they fell early enough for the driver or detector to see
them and stop the train in time.

On Sat, 25 Apr 2015 17:06:13 +0100, wrote:

On Sat, 25 Apr 2015 14:49:17 +0000 (UTC), Recliner
wrote:

Aren't there detectors at stations that will either stop a train or cut
power in the event that somebody falls onto the tracks.

Apparently not.

Skytrain in Vancouver has such a system, AIUI.

Yes, the discussion was whether the DLR should have such a system, too. It
is indeed slightly surprising that it doesn't. Perhaps the fear is of false
positives (eg, when a bit of rubbish triggers the detector -- you can just
imagine the local yobs experimenting to see just what it took to stop the
trains).

If the fatality rate is such that some measures are required could a
variant on the suicide pit be practical?
With DLR trains being reasonably light the supporting structure for
the rails could mainly be longitudinal beams leaving a larger
"pit"area in relation to the track than those on the Tube lines.
It wouldn't stop all as some people may still straddle a rail but no
system is really going to protect every one and at least there isn't a
negative rail for someone to get hung over .
Pits would bring their own problems, litter trap, drainage required
on ground level stations but othe wise they are a simple passive
measure where as detectors are another bit of onboard kit to test,
maintain ,go wrong.

Probably very hard/expensive to retrofit to existing stations,
however, for relatively little benefit.

On Sat, 25 Apr 2015 23:14:31 +0100
"Clive D. W. Feather" wrote:
In message ,
wrote:
Except the person who was killed fell on the track by accident apparently
12 seconds before the train ran over her. Unless the driver was asleep he'd
have had no problem stopping the train in time.

Is that so? It's not obvious: a main line train takes 90 seconds to stop

Yes it is so.

from 100 mph at the braking rates the signalling is designed for.

A 3-unit DLR train is 84 metres long. The braking system is designed for
0.6 m/s^2, so that means the train will enter the platform at 10 m/s and
take 16.7 seconds to stop. 12 seconds before that the train is doing
17.2 m/s and is 162 metres from the start of the platform.

A DLR train doing 17.2 m/s coming into a platform? In which universe?
Thats 38mph. If a DLR train ever got up to that speed it probably had to go and
have a lie down for a week. Say a far more realistic 20-25 mph which seems
to be the top speed these days almost everywhere.

Train doing 10m/s, stops at 1.2m/s. Even with a 1-2 second reaction time
you're sorted.

Next...

However, will the victim be visible at 162 metres from the platform?
Particularly if there's a curve on the track.

Who knows. Maybe at some they would be , at others not.

Will it be worth the cost? How much will it cost to add a driver to
every DLR train? If I recall the previous posting, we're talking about
one accident every 5 years and one suicide a year.

Umm, why would you need to add a driver? FFS - the train ops/captains/door
dollys/whatever they're called this month are already on the train, salaried
and do virtually nothing for their money from what I can see. Why would
putting them at the front be so onorous?

--
Spud

d wrote:

On Sat, 25 Apr 2015 23:14:31 +0100
"Clive D. W. Feather" wrote:
In message ,
d wrote:
Except the person who was killed fell on the track by accident
apparently 12 seconds before the train ran over her. Unless the
driver was asleep he'd have had no problem stopping the train in
time.

Is that so? It's not obvious: a main line train takes 90 seconds to
stop

Yes it is so.

from 100 mph at the braking rates the signalling is designed for.

A 3-unit DLR train is 84 metres long. The braking system is
designed for 0.6 m/s^2, so that means the train will enter the
platform at 10 m/s and take 16.7 seconds to stop. 12 seconds before
that the train is doing 17.2 m/s and is 162 metres from the start
of the platform.

A DLR train doing 17.2 m/s coming into a platform? In which universe?
Thats 38mph. If a DLR train ever got up to that speed it probably had
to go and have a lie down for a week. Say a far more realistic 20-25
mph which seems to be the top speed these days almost everywhere.

Train doing 10m/s, stops at 1.2m/s. Even with a 1-2 second reaction
time you're sorted.

DLR Bank - Lewisham, 11.06km, timetabled 26 min. Thats 7.1m/s average
including 14 intermediate stops, so the top speed must be much more
than 10m/s.

Peter Smyth

On Mon, 27 Apr 2015 18:52:11 +0000 (UTC)
"Peter Smyth" wrote:
wrote:
A DLR train doing 17.2 m/s coming into a platform? In which universe?
Thats 38mph. If a DLR train ever got up to that speed it probably had
to go and have a lie down for a week. Say a far more realistic 20-25
mph which seems to be the top speed these days almost everywhere.

Train doing 10m/s, stops at 1.2m/s. Even with a 1-2 second reaction
time you're sorted.

DLR Bank - Lewisham, 11.06km, timetabled 26 min. Thats 7.1m/s average
including 14 intermediate stops, so the top speed must be much more
than 10m/s.

Well, timetables and reality are 2 different things, but it must be flying
on the parts I don't use because on the bank - canary wharf section I reckon
it does 30mph absolute max.

--
Spud

wrote:
On Mon, 27 Apr 2015 18:52:11 +0000 (UTC)
"Peter Smyth" wrote:
d wrote:
A DLR train doing 17.2 m/s coming into a platform? In which universe?
Thats 38mph. If a DLR train ever got up to that speed it probably had
to go and have a lie down for a week. Say a far more realistic 20-25
mph which seems to be the top speed these days almost everywhere.

Train doing 10m/s, stops at 1.2m/s. Even with a 1-2 second reaction
time you're sorted.

DLR Bank - Lewisham, 11.06km, timetabled 26 min. Thats 7.1m/s average
including 14 intermediate stops, so the top speed must be much more
than 10m/s.

Well, timetables and reality are 2 different things, but it must be flying
on the parts I don't use because on the bank - canary wharf section I reckon
it does 30mph absolute max.

30mph = 13.4 m/s

On Wed, 29 Apr 2015 00:29:47 +0000 (UTC)
Recliner wrote:
wrote:
On Mon, 27 Apr 2015 18:52:11 +0000 (UTC)
"Peter Smyth" wrote:
d wrote:
A DLR train doing 17.2 m/s coming into a platform? In which universe?
Thats 38mph. If a DLR train ever got up to that speed it probably had
to go and have a lie down for a week. Say a far more realistic 20-25
mph which seems to be the top speed these days almost everywhere.

Train doing 10m/s, stops at 1.2m/s. Even with a 1-2 second reaction
time you're sorted.

DLR Bank - Lewisham, 11.06km, timetabled 26 min. Thats 7.1m/s average
including 14 intermediate stops, so the top speed must be much more
than 10m/s.

Well, timetables and reality are 2 different things, but it must be flying
on the parts I don't use because on the bank - canary wharf section I reckon
it does 30mph absolute max.

30mph = 13.4 m/s

Yes, and? It certainly doesn't do it entering stations. 20mph maybe.

Besides, I've been on a DLR train that did an emergency stop - presumably
when it lost its control signal - and took no time at all.

--
Spud