It has always seemed to me that the 750 volt 3rd rail is a bad
idea. Rather it is the idea that somebody (Sprague?) first thought of
and it got made permanent. Its drawbacks in its present form seem to
me to be :-

* The possibility of electrocuting somebody. Are there many
casualties? More difficult to answer; how much do the procedures to
avoid electrocution cost in direct and indirect costs?

* It too often gets covered with ice in winter (and wet leaves
in autumn?)

* The danger of electrocution means that voltages cannot be
raised to increase power delivery. Italian state railways (FS =
Ferrovia della Stato) started with 3000 volt overhead wires, but
everything has now been done so that they can increase the voltage to
6000 volts, so doubling the power that can be delivered.

So I have been thinking of the possibilities of shielding the
3rd rail. The shield would be made of springy plastic, with square
holes moulded in the bottom, to allow rainwater and leaves to drop out
of the bottom and cooling air to rise through them. The holes would be
too small to allow a hand to be put through and too far for a finger
to reach the 3rd rail.

The shield would be fitted by springing open the shield, and
pushing it upwards over the bottom of the 3rd rail. A cut will have to
be made on the train side at each insulator to fit the shield, and
some of the bottom grille cut away to allow it to be put over the
insulator. Keys projecting into the inner space will be clipped to the
lower web of the rail, thus allowing air to flow round the 3rd rail.
This requires plastic which will keep its spring for many years, and
this might be a problem.

Along the side of the top there is a slot which the train
pick-up shoe (more like a "tongue") goes through. It is under an
overhang to stop rain and leaves from getting in, but being at the top
it creates some chimney effect for cooling the 3rd rail.

The slot at the top would be too narrow and too far from
the 3rd rail to put hand or finger onto it. Suicide will still be
possible for somebody who wants to do it, but somebody who is on a
railway track and wants to commit suicide has plenty of other ways of
bringing it all to an end. An ACCIDENT is now very difficult.

To complete this would obviously be a 10 or 20 year project,
(even longer to replace some of the longer-lived stock with higher
voltage stock) but some of the benefits, such as no icing in winter,
would come immediately. To get everything lined up it obviously also
requires a standard of track laying better than some we have seen in
recent years. Is that good or bad?

There are shielded 3rd rails on the continent, but I'm afraid
I can't see Network Rail, with its many problems, and its difficulties
with the TOCs, undertaking a project like this, no matter how
worthwhile.

Michael Bell



________________________________________
| ___________________________________ |
| | | |
| | ||||||||||||||||||||||||||||| | |
| | || ____ _______________ | |
|__| || | | | | | |
|| | | |_ _| | |
||||||||||||||||||||| | | | 3rd | | |
| | | rail | | |
Pick-up tongue | | | | | |
| | | | | |
| | | | | |
| | | | / |
| \ / \ / |
| \ / \ / |
| // \ |
| /____________________\ | Shield
| __\ /___ | clipped
| | | | to lower
| | | | web of
| | | | rail
| |___________________________| |
|_______________________________|

Plastic grille at bottom.

Michael Bell wrote:
It has always seemed to me that the 750 volt 3rd rail is a bad idea.
snip
So I have been thinking of the possibilities of shielding the
3rd rail. snip

Other people have designed such systems too. There is one already in
operation in London - the DLR.

To complete this would obviously be a 10 or 20 year project,
(even longer to replace some of the longer-lived stock with higher
voltage stock) but some of the benefits, such as no icing in winter,
would come immediately.

Your design includes a plastic cover over the top of the rail. Doesn't this
prevent existing stock from using rails fitted with your plastic covers? I
don't understand how you intend to operate during the 10-20 year conversion
period.

Also, have you done any sort of cost-benefit analysis for this project?
--
Richard J.
(to e-mail me, swap uk and yon in address)

Michael Bell writes
There are shielded 3rd rails on the continent, but I'm afraid I
can't see Network Rail, with its many problems, and its difficulties
with the TOCs, undertaking a project like this, no matter how
worthwhile.

Protected third rail is used on the DLR. HSE would not allow any new
rail system to use unprotected third rail - although they will allow
extensions to existing systems.

From 1916 until around 1990, the Manchester Victoria-Bury service used
trains operating off a 1200V DC protected third rail - with a
side-contact. This system was replaced by overhead wires when the route
was converted for use as part of the Metrolink system.

A couple of pics which may help to illustrate the Bury system;
http://www.therailwaycentre.com/EMU%...le/504_asbuilt
http://easyweb.easynet.co.uk/~gsgleaves/gauge.jpg

--
Dave

In article , Richard J.
wrote:
Michael Bell wrote:
It has always seemed to me that the 750 volt 3rd rail is a bad idea.
snip
So I have been thinking of the possibilities of shielding the
3rd rail. snip

Other people have designed such systems too. There is one already in
operation in London - the DLR.

To complete this would obviously be a 10 or 20 year project,
(even longer to replace some of the longer-lived stock with higher
voltage stock) but some of the benefits, such as no icing in winter,
would come immediately.

Your design includes a plastic cover over the top of the rail. Doesn't this
prevent existing stock from using rails fitted with your plastic covers? I
don't understand how you intend to operate during the 10-20 year conversion
period.


Obviously the fleet has to be modified first. That's the smallest part
of the job!

Also, have you done any sort of cost-benefit analysis for this project?

No, I have done no cost-benefit analyis. But if DLR (which I should
have thought of) have done it, and foreign systems have done it, then
they must have made some sort of calculation.

--

Michael

On Fri, 8 Aug 2003 23:43:59 +0100, Michael Bell
wrote:

It has always seemed to me that the 750 volt 3rd rail is a bad
idea. Rather it is the idea that somebody (Sprague?) first thought of
and it got made permanent. Its drawbacks in its present form seem to
me to be :-

* The possibility of electrocuting somebody. Are there many
casualties? More difficult to answer; how much do the procedures to
avoid electrocution cost in direct and indirect costs?

There aren't as many electrocutions as you may think there is. In fact
there are less deaths on Third Rail Electrifaction areas than there
are on Overhead Lines which has a even more dangerous 25kV.

* It too often gets covered with ice in winter (and wet leaves
in autumn?)

Leaves in the autumn are not a problem with third rail. And deicing
trains are used with great effect on the third rail. The only time
icing of the third rail becomes a problem is because Network Rail
Controllers fail to predict a heavy frost/ snow fall.

* The danger of electrocution means that voltages cannot be
raised to increase power delivery. Italian state railways (FS =
Ferrovia della Stato) started with 3000 volt overhead wires, but
everything has now been done so that they can increase the voltage to
6000 volts, so doubling the power that can be delivered.

Increase in volt to 1000 volts DC was muted some years ago, instead
more intermediate Traction Parallel Huts where built.

So I have been thinking of the possibilities of shielding the
3rd rail. The shield would be made of springy plastic, with square
holes moulded in the bottom, to allow rainwater and leaves to drop out
of the bottom and cooling air to rise through them. The holes would be
too small to allow a hand to be put through and too far for a finger
to reach the 3rd rail.

Again leaves aren't a problem as is rain water. The DLR have a a
bottom contact third rail which is covered. the Manchester to Bury
line, now part of the Manchester Tram link, used to have a side
contact third rail that was covered and this was 1500 volts dc.
If a risk assessment was done of the Third Rail system, covering
wouldn't be cost productive as electropcution by third rail is
exceptionally low.
As no one except authorised personell should be on the line, one's
trained in third rail areas, no one should be putting fingers any
where near it. Trepassers have more than adequate warning of the
presence of the third rail. And anyone strayiong on the line, knw they
shouldn't be there and deserve to be hurt if they are.

The shield would be fitted by springing open the shield, and
pushing it upwards over the bottom of the 3rd rail. A cut will have to
be made on the train side at each insulator to fit the shield, and
some of the bottom grille cut away to allow it to be put over the
insulator. Keys projecting into the inner space will be clipped to the
lower web of the rail, thus allowing air to flow round the 3rd rail.
This requires plastic which will keep its spring for many years, and
this might be a problem.

Air around the conductor rail???? Plastic against the conductor rail
will not cause it to heat up.

Along the side of the top there is a slot which the train
pick-up shoe (more like a "tongue") goes through. It is under an
overhang to stop rain and leaves from getting in, but being at the top
it creates some chimney effect for cooling the 3rd rail.

You're obsessed with leaves. The tolerances of the shoe running on
the thrid rail head are such that there would be a large gap for you
to put your fingers in!!!!!!! Not all train shoes are the same,
different units have different types, sizes and shapes.

The slot at the top would be too narrow and too far from
the 3rd rail to put hand or finger onto it. Suicide will still be
possible for somebody who wants to do it, but somebody who is on a
railway track and wants to commit suicide has plenty of other ways of
bringing it all to an end. An ACCIDENT is now very difficult.

Funny enough, suicides don't commit sucide with the third rail, never
heard of any cases of this. They tend to jump in front of those big
iron things called trains. Perhaps you would like the exterior of
these padded with cotton wool to lessen the impact of suicide
attempts!!!!!!!!!

To complete this would obviously be a 10 or 20 year project,
(even longer to replace some of the longer-lived stock with higher
voltage stock) but some of the benefits, such as no icing in winter,
would come immediately. To get everything lined up it obviously also
requires a standard of track laying better than some we have seen in
recent years. Is that good or bad?

Are you insane. Trains can run up to 100mph on thrid rail systems, and
possibly higher, even with just 750 volts dc. The benefits of a
covered third rail are nil compared to the cost involved in covering
it!!! And what has better standards of track laying got to do with it.

There are shielded 3rd rails on the continent, but I'm afraid
I can't see Network Rail, with its many problems, and its difficulties
with the TOCs, undertaking a project like this, no matter how
worthwhile.

The only problems Network Rail have got is the British Government
continually interfering with the attempts of honest dedicated
railwaymen trying to give the public a train service.

C

Life without sex just isn't life.
Make love not war!

"Christine" wrote in message
...
On Fri, 8 Aug 2003 23:43:59 +0100, Michael Bell
wrote:

It has always seemed to me that the 750 volt 3rd rail is a bad
idea. Rather it is the idea that somebody (Sprague?) first thought of
and it got made permanent. Its drawbacks in its present form seem to
me to be :-

* The possibility of electrocuting somebody. Are there many
casualties? More difficult to answer; how much do the procedures to
avoid electrocution cost in direct and indirect costs?

There aren't as many electrocutions as you may think there is. In fact
there are less deaths on Third Rail Electrifaction areas than there
are on Overhead Lines which has a even more dangerous 25kV.

A track worker was killed just this week (one of the reasons for the '9 hour
Southampton to London' fiasco widely reported).

* It too often gets covered with ice in winter (and wet leaves
in autumn?)

Leaves in the autumn are not a problem with third rail. And deicing
trains are used with great effect on the third rail. The only time
icing of the third rail becomes a problem is because Network Rail
Controllers fail to predict a heavy frost/ snow fall.

* The danger of electrocution means that voltages cannot be
raised to increase power delivery. Italian state railways (FS =
Ferrovia della Stato) started with 3000 volt overhead wires, but
everything has now been done so that they can increase the voltage to
6000 volts, so doubling the power that can be delivered.

Increase in volt to 1000 volts DC was muted some years ago, instead
more intermediate Traction Parallel Huts where built.

So I have been thinking of the possibilities of shielding the
3rd rail. The shield would be made of springy plastic, with square
holes moulded in the bottom, to allow rainwater and leaves to drop out
of the bottom and cooling air to rise through them. The holes would be
too small to allow a hand to be put through and too far for a finger
to reach the 3rd rail.

Again leaves aren't a problem as is rain water. The DLR have a a
bottom contact third rail which is covered. the Manchester to Bury
line, now part of the Manchester Tram link, used to have a side
contact third rail that was covered and this was 1500 volts dc.
If a risk assessment was done of the Third Rail system, covering
wouldn't be cost productive as electropcution by third rail is
exceptionally low.
As no one except authorised personell should be on the line, one's
trained in third rail areas, no one should be putting fingers any
where near it. Trepassers have more than adequate warning of the
presence of the third rail. And anyone strayiong on the line, knw they
shouldn't be there and deserve to be hurt if they are.

So, small children (who, for whatever reason, may not have been told about
the dangers of going near the railway), or persons who accidentally fall of
a platform 'deserve to be hurt'. That is rather harsh!


The shield would be fitted by springing open the shield, and
pushing it upwards over the bottom of the 3rd rail. A cut will have to
be made on the train side at each insulator to fit the shield, and
some of the bottom grille cut away to allow it to be put over the
insulator. Keys projecting into the inner space will be clipped to the
lower web of the rail, thus allowing air to flow round the 3rd rail.
This requires plastic which will keep its spring for many years, and
this might be a problem.

Air around the conductor rail???? Plastic against the conductor rail
will not cause it to heat up.

Along the side of the top there is a slot which the train
pick-up shoe (more like a "tongue") goes through. It is under an
overhang to stop rain and leaves from getting in, but being at the top
it creates some chimney effect for cooling the 3rd rail.

You're obsessed with leaves. The tolerances of the shoe running on
the thrid rail head are such that there would be a large gap for you
to put your fingers in!!!!!!! Not all train shoes are the same,
different units have different types, sizes and shapes.

The slot at the top would be too narrow and too far from
the 3rd rail to put hand or finger onto it. Suicide will still be
possible for somebody who wants to do it, but somebody who is on a
railway track and wants to commit suicide has plenty of other ways of
bringing it all to an end. An ACCIDENT is now very difficult.

Funny enough, suicides don't commit sucide with the third rail, never
heard of any cases of this. They tend to jump in front of those big
iron things called trains. Perhaps you would like the exterior of
these padded with cotton wool to lessen the impact of suicide
attempts!!!!!!!!!

To complete this would obviously be a 10 or 20 year project,
(even longer to replace some of the longer-lived stock with higher
voltage stock) but some of the benefits, such as no icing in winter,
would come immediately. To get everything lined up it obviously also
requires a standard of track laying better than some we have seen in
recent years. Is that good or bad?

Are you insane. Trains can run up to 100mph on thrid rail systems, and
possibly higher, even with just 750 volts dc. The benefits of a
covered third rail are nil compared to the cost involved in covering
it!!! And what has better standards of track laying got to do with it.

The third rail system is an example of a historical solution that, if we
were starting from scratch, we would not dream of using nowadays. However,
because it is so extensive the cost of modifying or replacing it outweighs
the resulting safety benefit.


There are shielded 3rd rails on the continent, but I'm afraid
I can't see Network Rail, with its many problems, and its difficulties
with the TOCs, undertaking a project like this, no matter how
worthwhile.

The only problems Network Rail have got is the British Government
continually interfering with the attempts of honest dedicated
railwaymen trying to give the public a train service.

I really don't think you can blame the Government for all of the railways
woes (although their attempts to try and 'make things better' have often
done more harm than good).


C

Life without sex just isn't life.
Make love not war!

From: Michael Bell
Date: 08/08/2003 23:43 GMT Daylight Time

It has always seemed to me that the 750 volt 3rd rail is a bad
idea.

Too right! Massive amperages, high resistances, huge numbers of substations in
relation to the length of a line. It's an idea that's really past its sell by
date. If you want to electrify, do it properly with 25Kv at 50 Hertz in a wire
up on some sticks. Tinkering about with 750v DC is about as much good as
rearranging the deckchairs on the deck of the "Titanic".

Michael Bell wrote in message ...
It has always seemed to me that the 750 volt 3rd rail is a bad
idea. Rather it is the idea that somebody (Sprague?) first thought of
and it got made permanent. Its drawbacks in its present form seem to
me to be :-

* The possibility of electrocuting somebody. Are there many
casualties? More difficult to answer; how much do the procedures to
avoid electrocution cost in direct and indirect costs?

* It too often gets covered with ice in winter (and wet leaves
in autumn?)

So does the Overhead Line.......

* The danger of electrocution means that voltages cannot be
raised to increase power delivery. Italian state railways (FS =
Ferrovia della Stato) started with 3000 volt overhead wires, but
everything has now been done so that they can increase the voltage to
6000 volts, so doubling the power that can be delivered.


Well how many people do you know that get up in the morning and take
the dog for a walk down the third rail? I know some idiots do it but
the majority don't!

So I have been thinking of the possibilities of shielding the
3rd rail. The shield would be made of springy plastic, with square
holes moulded in the bottom, to allow rainwater and leaves to drop out
of the bottom and cooling air to rise through them. The holes would be
too small to allow a hand to be put through and too far for a finger
to reach the 3rd rail.

And whos going to pay for this?

To be honest I'm supprised your not complaining at overhead
powerlines, street cables etc. Someone could easily kill themselves by
sticking a knitting needle into a plug socket and turning it on, and
many places have high voltage sockets for cleaning equipment. Are you
one of these doughnuts who is trying to dieselise the country?

"Acrosticus" wrote in message
...
From: Michael Bell
Date: 08/08/2003 23:43 GMT Daylight Time

It has always seemed to me that the 750 volt 3rd rail is a bad
idea.

Too right! Massive amperages, high resistances, huge numbers of
substations in
relation to the length of a line. It's an idea that's really past its sell
by
date. If you want to electrify, do it properly with 25Kv at 50 Hertz in a
wire
up on some sticks. Tinkering about with 750v DC is about as much good as
rearranging the deckchairs on the deck of the "Titanic".



And as soon as we get some windy weather all the overhead lines come down
and the entire rail network is screwed.

The Equalizer wrote:
"Acrosticus" wrote in message
...
From: Michael Bell
Date: 08/08/2003 23:43 GMT Daylight Time

It has always seemed to me that the 750 volt 3rd rail is
a bad
idea.

Too right! Massive amperages, high resistances, huge
numbers of substations in relation to the length of a
line. It's an idea that's really past its sell by date. If
you want to electrify, do it properly with 25Kv at 50
Hertz in a wire up on some sticks. Tinkering about with
750v DC is about as much good as rearranging the
deckchairs on the deck of the "Titanic".



And as soon as we get some windy weather all the overhead
lines come down and the entire rail network is screwed.

Not all, just that which was put up on the cheap.