I've always wondered - are sleepers actually attached to the ground
they rest on, or are they just held there by the weight of the rails?

Rich wrote:

> I've always wondered - are sleepers actually attached to the ground
> they rest on, or are they just held there by the weight of the rails?


AIUI, they're locked in by the ballast, hence the importance of a good
"shoulder" of ballast along the sides of the track. The individual
stones should have nice sharp angles so that they interlock with each
other and resist both forwards and sideways creep of the track.

Some sleepers are set in concrete of course, e.g. in slab track, which
holds them
more rigidly.

But I Am Not An Engineer, and I expect other posters can give you more
information.
-- 
Pat Ricroft, City of Salford, UK
================================

Rich wrote:

> I've always wondered - are sleepers actually attached to the ground
> they rest on, or are they just held there by the weight of the rails?


As Pat replied well, they are not tied to the ground (except in
slabtrack, where the sleepers are cast into a continues slab of
concrete along the line [1]), they are purely there under their own
weight. They are pretty hefty:
For concrete sleepers, EF28=260Kg. F35S=315Kg, and possibly the
heftiest of all - APC01=435Kg! The rail is also heavy - The latest rail
section is NR60/UIC60 - 60kg per metre length. Thus, the track is not
going to lift up! Timbers are prety hefty too, although I have no
numbers for them, so don't know exactly. Steel sleepers are a bit
different - they are very light, and are held in place, partly through
the weight of the rails, and partly through the ballast. If you ever
see steel sleepers piled up, awaiting installation, you'll notice they
curve down at the end and have a long diagonal section that goes down
into the ballast, and ballast is placed on top of them, holding them in
place.

It's held in horizontal position by the ballast - this is why, as Pat
said, there needs to be a good 'shoulder' of ballast to keep the track
in a good alignment. Some people often think there is a lot of wasted
ballast to the sides of the track, when in fact, this is the most
useful part - it provides lateral restraint. Longitudinal restraint is
also important, so having a good amount of ballast, well, everywhere,
is vital in order to maintain good track alignent. It become more
critical for CWR - the forces with which the track is trying to move
are greater, if the stresses in the rail aren't right, and there is a
lot of track where that is the case, hence all the speed restictions in
the summer months.

HTH!

Phil

[1] Yes, I know it's not actually continuous, but that's too much
detail for this kind of answer...

On 5/9/05 3:39 pm, in article
1125931159.581404.209600@g49g2000cwa.googlegroups.com, "Phil Holbourn"
 wrote:


> 
> As Pat replied well, they are not tied to the ground (except in
> slabtrack, where the sleepers are cast into a continues slab of
> concrete along the line [1]), they are purely there under their own
> weight. They are pretty hefty:
> For concrete sleepers, EF28=260Kg. F35S=315Kg, and possibly the
> heftiest of all - APC01=435Kg! The rail is also heavy - The latest rail
> section is NR60/UIC60 - 60kg per metre length. Thus, the track is not
> going to lift up!


Having done a bit of work on the broad gauge line at Didcot many years ago,
I know that anything to do with railway track is bloody heavy, and that was
just with roughly 59 pound bridge rail; the modern stuff is much heavier.
Even a Pandrol clip is quite a large chunk of metal if you actually pick one
up,

I remember seeing a wartime picture taken at the Southern Railway foundry
and track works which used to be near Southampton, Redbridge I think it was.
The picture was of a woman worker there holding up a  pair of rail chairs,
one in each hand, at shoulder height, and they were quite large ones; that's
a lot of iron to hold up.  I think the picture was in a book called 'Making
Tracks', published at the time of the works closure.

This place: http://www.railwaysleeper.com/ sells new and used wooden
sleepers, telegraph poles etc., and gives an idea of the size, weight and
cost of the various types (I never knew there were so many, nor so many uses
for them).  What did surprise me is that new hardwood ones only cost about
four times as much as the worst, grade 4 'reject' used ones.  Quite an
interesting site, with lots of pictures of projects built with old sleepers.