In article
-septembe
r.org, (Recliner) wrote:

wrote:
On Tue, 16 Aug 2016 11:04:06 +0100
Neil Williams wrote:
On 2016-08-16 09:50:19 +0000, Recliner said:

It's probably better than most cab firms. The reason that black cabs
hate Uber is that it's so popular with customers, not that it provides
poor customer service.

The black cab dislike of Uber is close to the DOO debates on Southern -
technology is obviating the need for a job, and those in that job
understandably don't like it.

We'll have the same for the abolition of train *drivers* within 20
years. Guard-only operation like DLR is more likely to be the future
(or full automation of city metro systems with staff on specific busy
platforms only); DOO is a short-term blip.

Nearly 50 years and counting is a bit more than short term.

I wouldn't be so sure of that. ATO on a slow metro system is one thing,
having no one at the front on an express is another matter entirely.
Until trains have sensors at least as good as the human eye to see any
obstructions ahead it won't happen. The same issues apply to self
driving cars. Its no use the computer seeing all the cars around it in
precise detail if it misses the pile up 200m ahead and brakes way too
late.

Can the drivers of 200mph expresses see far enough ahead to be able to
have any material ability to slow or stop the train if they see an
obstruction or track problem?

They can't see far enough ahead to do anything useful to avoid a tractor on
an occupation crossing as at Roudham.

--
Colin Rosenstiel

On Tue, 16 Aug 2016 11:23:28 -0500
wrote:
Can the drivers of 200mph expresses see far enough ahead to be able to
have any material ability to slow or stop the train if they see an
obstruction or track problem?

They can't see far enough ahead to do anything useful to avoid a tractor on
an occupation crossing as at Roudham.

Useful like what, steer out the way?

I'm curious that a lot of people on this group seem to believe that the
speed a train hits something makes no difference. 100mph, 200mph , who cares
eh? All the same.

--
Spud

wrote:
On Tue, 16 Aug 2016 11:23:28 -0500
wrote:
Can the drivers of 200mph expresses see far enough ahead to be able to
have any material ability to slow or stop the train if they see an
obstruction or track problem?

They can't see far enough ahead to do anything useful to avoid a tractor on
an occupation crossing as at Roudham.

Useful like what, steer out the way?

I'm curious that a lot of people on this group seem to believe that the
speed a train hits something makes no difference. 100mph, 200mph , who cares
eh? All the same.

The speed reduction with a high speed train will be trivial. By the time
the driver spots the obstruction, and decides to brake, the train will
almost be on top of it. At 320km/h, the train will have moved about 100m
before the driver can even start to brake. There may be some latency in the
braking, so by the time the full brake application starts, the train may
well have travelled another 100m.

So if the obstruction was only 200m away, the train may still be travelling
at full speed. Even if it was 500m away, the speed will probably still be
close to 300 km/h. The driver would be best advised to retreat from the
cab and move further back in the train in the few seconds before the crash,
though the power car or driving car is highly likely to be thrown off the
tracks, and if it hits anything head-on, the damage will be catastrophic.
Slowing the train from 320km/h to a bit less will make almost no
difference. So at least one less life would be at risk if there was no
driver in the cab.

Where the driver might be needed is during slow speed manouvres near
stations, not the high speed sections of the line.

On Wed, 17 Aug 2016 09:13:10 -0000 (UTC)
Recliner wrote:
The speed reduction with a high speed train will be trivial. By the time

I disagree. Kinetic energy is derived from velocity squared, so a small change
in velocity can make a large change in the amount of energy that needs to
be dissapated.

So if the obstruction was only 200m away, the train may still be travelling
at full speed. Even if it was 500m away, the speed will probably still be
close to 300 km/h. The driver would be best advised to retreat from the

You're forgetting however that the driver will have put the train into braking
mode. An ATO train would still have full power to the motors at the point of
impact and possibly beyond too. In fact thats what happened in the moorgate
crash - albeit with a suicidal driver and not a computer - with the back of
the train actively shoving the front up over the sand drag.

Where the driver might be needed is during slow speed manouvres near
stations, not the high speed sections of the line.

You'll certainly need a pair of eyes pulling into platforms.

--
Spud

On 17.08.16 10:13, Recliner wrote:
wrote:
On Tue, 16 Aug 2016 11:23:28 -0500
wrote:
Can the drivers of 200mph expresses see far enough ahead to be able to
have any material ability to slow or stop the train if they see an
obstruction or track problem?

They can't see far enough ahead to do anything useful to avoid a tractor on
an occupation crossing as at Roudham.

Useful like what, steer out the way?

I'm curious that a lot of people on this group seem to believe that the
speed a train hits something makes no difference. 100mph, 200mph , who cares
eh? All the same.

The speed reduction with a high speed train will be trivial. By the time
the driver spots the obstruction, and decides to brake, the train will
almost be on top of it. At 320km/h, the train will have moved about 100m
before the driver can even start to brake. There may be some latency in the
braking, so by the time the full brake application starts, the train may
well have travelled another 100m.

What do you mean by latency, the amount of time that it takes for the
helm to respond?


So if the obstruction was only 200m away, the train may still be travelling
at full speed. Even if it was 500m away, the speed will probably still be
close to 300 km/h. The driver would be best advised to retreat from the
cab and move further back in the train in the few seconds before the crash,
though the power car or driving car is highly likely to be thrown off the
tracks, and if it hits anything head-on, the damage will be catastrophic.


Slowing the train from 320km/h to a bit less will make almost no
difference. So at least one less life would be at risk if there was no
driver in the cab.

Where the driver might be needed is during slow speed manouvres near
stations, not the high speed sections of the line.

I've heard drivers on RENFE indicate that he could not drive the train
without a computer, whilst the computer would not be able to operate the
train without a driver.

wrote:
On 17.08.16 10:13, Recliner wrote:
wrote:
On Tue, 16 Aug 2016 11:23:28 -0500
wrote:
Can the drivers of 200mph expresses see far enough ahead to be able to
have any material ability to slow or stop the train if they see an
obstruction or track problem?

They can't see far enough ahead to do anything useful to avoid a tractor on
an occupation crossing as at Roudham.

Useful like what, steer out the way?

I'm curious that a lot of people on this group seem to believe that the
speed a train hits something makes no difference. 100mph, 200mph , who cares
eh? All the same.

The speed reduction with a high speed train will be trivial. By the time
the driver spots the obstruction, and decides to brake, the train will
almost be on top of it. At 320km/h, the train will have moved about 100m
before the driver can even start to brake. There may be some latency in the
braking, so by the time the full brake application starts, the train may
well have travelled another 100m.

What do you mean by latency, the amount of time that it takes for the
helm to respond?

Both the driver's and the system's delays. The driver, having spotted a
distant possible obstruction has to decide whether to brake, and then
operate the controls; and there is latency in the system: the brakes on a
long train with dozens of axles don't respond nearly as quickly as a car's
brakes.



So if the obstruction was only 200m away, the train may still be travelling
at full speed. Even if it was 500m away, the speed will probably still be
close to 300 km/h. The driver would be best advised to retreat from the
cab and move further back in the train in the few seconds before the crash,
though the power car or driving car is highly likely to be thrown off the
tracks, and if it hits anything head-on, the damage will be catastrophic.


Slowing the train from 320km/h to a bit less will make almost no
difference. So at least one less life would be at risk if there was no
driver in the cab.

Where the driver might be needed is during slow speed manouvres near
stations, not the high speed sections of the line.

I've heard drivers on RENFE indicate that he could not drive the train
without a computer, whilst the computer would not be able to operate the
train without a driver.

Computers already drive plenty of trains using ATO, and have done for
decades, safely and reliably. I'd rather trust a computer to drive a fast
train on a dedicated track, than a human trying to follow the computer's
orders. At most, the human supervisor should be there to override the
computer at times of emergency or when running at low speed on conventional
tracks (just as airliners are flown automatically most of the time, but are
steered manually on the airfield).