On May 26, 12:51*am, lonelytraveller
wrote:
The post office railway goes from Paddington to Whitechapel with stops
at Oxford Circus, Rathbone Place, Mount Pleasant, and Liverpool
Street. It also passes along Oxford Street from the vicinity of Bond
Street.

The stop on Rathbone Place is very near the proposed Dean Street
"Western Ticket Hall" for the Tottenham Court Road station on
Crossrail.

Mount Pleasant is about 5 minutes walk from Farringdon, in the heart
of Clerkenwell, adjacent to the Thameslink and Circle/Met lines, in a
busy area which could do with a tube station.

The post office railway is disused.

Why didn't they just widen the tunnels and reuse them for Crossrail,
instead of digging hugely expensive new ones?

Because cash strapped Royal Mail are hiring them out to a Turkish
drugs gang.

In message , d
writes

Tunnels arn't dug with
picks and shovels any more - a TBM won't care if it has to dig the whole
tunnel itself or theres a small tunnel already there , it will take more or
less the same time. The only difference will be in the amount of spoil
needing to be carried away.

Which reminds me that there were several proposals to use the Post
Office Railway to remove spoil from the central area. I haven't heard
anything more of the suggestion, though.
--
Paul Terry

"Paul Terry" wrote in message
...
In message
,
lonelytraveller writes

The post office railway is disused.

Why didn't they just widen the tunnels and reuse them for Crossrail,
instead of digging hugely expensive new ones?

It's not deep enough - the Post Office Railway is on average 21m below the
surface, although the stations are virtually at basement level (and so the
tunnels also have steep 20% gradients either side of stations). Crossrail
in the central area is up to 36m below the surface. Also, the Post Office
Railway doesn't have a straight enough alignment - it runs north of Oxford
Street, curving up to Wimpole Street and then coming back south before the
big loop up to Mount Pleasant.

It is a shame, though, that it hasn't been put to some good use since its
closure.

Like turning it into a museum perhaps

tim

On Wed, 26 May 2010, d wrote:

Tunnels arn't dug with picks and shovels any more - a TBM won't care if
it has to dig the whole tunnel itself or theres a small tunnel already
there

Yes it will - TBMs are built for digging through clay, gravel, and the
like. Sticking a bloody great cast-iron pipe like the PO railway end-on in
its way will completely bugger it.

tom

--
uk.local groups TO BE RENAMED uk.lunatic.fringe groups

On 26/05/2010 07:18, Paul Terry wrote:
In message
,
lonelytraveller writes

The post office railway is disused.

Why didn't they just widen the tunnels and reuse them for Crossrail,
instead of digging hugely expensive new ones?

It's not deep enough - the Post Office Railway is on average 21m below
the surface, although the stations are virtually at basement level (and
so the tunnels also have steep 20% gradients either side of stations).
Crossrail in the central area is up to 36m below the surface. Also, the
Post Office Railway doesn't have a straight enough alignment - it runs
north of Oxford Street, curving up to Wimpole Street and then coming
back south before the big loop up to Mount Pleasant.

It is a shame, though, that it hasn't been put to some good use since
its closure.

Any potential excursions for the public?

IIRC, the railway was never used by postal employees for transport
purposes.

On Wed, 26 May 2010 20:41:10 +0100, Tom Anderson
wrote:

On Wed, 26 May 2010, d wrote:

Tunnels arn't dug with picks and shovels any more - a TBM won't care if
it has to dig the whole tunnel itself or theres a small tunnel already
there

Yes it will - TBMs are built for digging through clay, gravel, and the
like. Sticking a bloody great cast-iron pipe like the PO railway end-on in
its way will completely bugger it.


But you wouldn't do that. Tunnel miners would dismantle the segmental
lining of the smaller diameter tunnel, ring by ring, a short distance
in front of the main tunneling shield. The shield would then move
forward, excavating as it went, and the new, larger diameter lining
would be installed at the rear of the shield.

This is all routine tunnelling work. The only complication is the
need to stop any excavation of the larger diameter tunnel while miners
dismantle the lining of the smaller diameter tunnel. But that would
happen simultaneously with the building of a ring of new lining, so it
wouldn't actually need to stop progress.

However, what would kill the idea stone dead is that the PO railway
tunnel is on the wrong alignment and is far too shallow for Crossrail.
Also, it is only one tunnel and Crossrail needs two. You cannot build
one alongside because the ground at that depth is almost certainly now
peppered with bearing piles for buildings that have been built since
the PO railway.

So, a complete non-starter.

On 26/05/2010 15:04, Paul Terry wrote:
In message , d writes

Tunnels arn't dug with
picks and shovels any more - a TBM won't care if it has to dig the whole
tunnel itself or theres a small tunnel already there , it will take
more or
less the same time. The only difference will be in the amount of spoil
needing to be carried away.

Which reminds me that there were several proposals to use the Post
Office Railway to remove spoil from the central area. I haven't heard
anything more of the suggestion, though.

Wouldn't it be easier to remove the spoil by the Crossrail tunnels they
had just dug?

In message , Basil Jet
writes

On 26/05/2010 15:04, Paul Terry wrote:

Which reminds me that there were several proposals to use the Post
Office Railway to remove spoil from the central area. I haven't heard
anything more of the suggestion, though.

Wouldn't it be easier to remove the spoil by the Crossrail tunnels they
had just dug?

The idea was to use the PO Railway to remove the huge amounts of spoil
from the shafts and station boxes that are currently being dug. The
actual tunnel boring is not due to start until late 2011 but when it
does, the spoil from that will indeed be removed by rail through the
tunnel itself.

Apparently the idea of adapting the PO Railway for spoil transportation
was considered by the Crossrail board, but rejected for a number of
fairly obvious reasons, so lorries are being used instead at the moment.
--
Paul Terry

In message , "
writes

On 26/05/2010 07:18, Paul Terry wrote:
In message
,
lonelytraveller writes

The post office railway is disused.

It is a shame, though, that it hasn't been put to some good use since
its closure.

Any potential excursions for the public?

A miniature underground heritage line in the middle of central London
could be a marvellous tourist attraction, even if passengers don't get
to see much out of the window.

IIRC, the railway was never used by postal employees for transport
purposes.

No, but it did have a carriage with seats for VIPs, hauled by a battery
loco. I have a feeling George V got a ride, and certainly John Noakes
did for Blue Peter some time in the 1970s.

I don't know if any really serious track bashers ever posted themselves
in large cardboard containers to try to do the line.
--
Paul Terry

Why didn't they just widen the tunnels and reuse them for Crossrail,
instead of digging hugely expensive new ones?

I will ignore the geometric aspects of the design of a low speed
passenger less railway vs a modern faster mainline railway.

But from having worked on some early options for tunnelled schemes
through London in the vicinity of the PO railway just how many sewers,
tunnels, etc. are down there. To enlarge the tunnel would bring you
even closer to some of these and require techniques such as grouting
and ground freezing to be used assuming that these are possible as
sufficient clearance may not exist. A 2.75m internal diameter would
need to be extended to around 6m.

OC