In message , at 03:52:01
on Tue, 26 Apr 2011, remarked:

And 2 busway tracks takes up a shed load more room than even a double
railway line.

Actually not, that's the point - it fits in the same space. Or do
you have some mythical trains that are narrower than a bus, so
they can squeeze through a smaller gap?

Except when it doesn't. For example, Trumpington cutting was a double
track railway in 1951 (to Bedford), but is now single track busway plus
maintenance track.

Roland is overlooking the maintenance track which is what prevents the
busway fitting within the railway alignment. It's being sold as a free
cycleway but it's actually what has cut capacity considerably on the
busway in places.

It's another case of a combination of thread drift and people not
comparing like with like.

The comments about width started off when I observed that one objection
to re-opening an old railway alignment in Nottingham was the loss of a
nature trail. That was countered by an observation that railways take up
less space than a guided bus and therefore the nature trail could
co-exist. Theo has posted a photo of an old trackbed with a single track
preserved railway and a footpath alongside.

Given that we were told that it had "most of the track and stations
still in situ" we must conclude that the poster in question was wanting
to restore a single track railway, but it's a shame it wasn't always
next to what I think was the only remaining platforms:

http://www.disused-stations.org.uk/h/histon/histon4.jpg

Yes, a twin track busway with cycle/maintenance path is wider than a
railway, but not wider than a two-track railway and nature trail. As far
as I'm concerned the only place that width matters very much is through
bridge holes.

The other factor overlooked is that trains only require the headroom of
single deck buses. Most buses used in Cambridge are double deck (for
capacity reasons). The Southern section of the guideway is available to
single deck buses only due to the low height of the bridges. On the
Northern section the track below bridges has had to be lowered in order to
accommodate double deckers. Luckily there aren't many bridges there but
there will be few through buses to Addenbrooke's Hospital and Trumpington
from the North because of the limitations.

And very few through[1] cast.iron trains, I expect. (another case of
comparing like with like).

[1] Even reaching Cambridge station requires using a substantial
investment from Network Rail to get from the Science Park, let alone
re-opening south towards the Trumpington P&R.
--
Roland Perry

In message , at 08:45:52 on Tue, 26 Apr
2011, d remarked:
Most of the weight a bridge has to support is its own weight. When you
get into those sorts of tonnages the weight of the vehicle crossing it
becomes only a small percentage of the total weight so the overall structure
of a busway bridge I suspect is not much less than that of a railway bridge.

Let's say 90% of the weight of the bridge is required to keep itself up, and
only 10% is represented by the safe load above it. That would indicate that
a bridge for a 14 ton bus would need to weigh 140 tons. Are you suggesting
you could run a 150 ton train across such a bridge, rather than needing a
1500 ton construction?

I don't know. What I do know is that modern road bridges and viaducts to me
seem to be very over engineered given the total weight they'd ever be expected
to carry. Eg , that M1 viaduct that had a fire underneath.

That's built to carry three lanes of 40 ton HGVs.

Rail bridges OTOH seem to be somewhat slender in comparison.

The busway bridge is pretty slender too. Here's someone's picture of it
under construction.

http://mw2.google.com/mw-panoramio/p...m/12999233.jpg

A bus is narrower than a train, you can't get away from that basic fact. And

Not by much in this country. Buses are what, 2.5 metres wide? The UK loading
gauge is 2.8 max.

Buses and busways are narrower than trains and their tracks. The only
wild card is whether you have a pathway beside them.

There isn't a direct road between the villages which the busway connects, so
it would be very hard to run a bus in the absence of the busway. The bigger
problem is that those villages won't create enough custom to fill a bus
every 20 minutes, let alone a train.

True, but a rail link from huntingdon to cambridge via ST Ives may well have
done ,

The route from St Ives to Huntingdon has only ever been speculation,
especially over the route it might take (the old trackbed's not
available for almost the entire length). Every suggestion I've seen
results in joining the ECML from the north, and the folks keenest on
reopening the line finish their route at "Huntingdon East" conveniently
not specifying the final mile.

coupled with the fact that it would have provided a useful diversion
route for the ECML.

Single track and non-electrified (ignoring the reverse at Huntingdon for
a moment) does not make a very useful diversion.
--
Roland Perry

On Tue, 26 Apr 2011 11:22:27 +0100
Roland Perry wrote:
I don't know. What I do know is that modern road bridges and viaducts to me
seem to be very over engineered given the total weight they'd ever be expected
to carry. Eg , that M1 viaduct that had a fire underneath.

That's built to carry three lanes of 40 ton HGVs.

Even 3 HGVs only weigh the same as a single locomotive. A rail bridge may have
to carry 2 locomotives plus their trains at the same time.

Rail bridges OTOH seem to be somewhat slender in comparison.

The busway bridge is pretty slender too. Here's someone's picture of it
under construction.

http://mw2.google.com/mw-panoramio/p...m/12999233.jpg

It would be interesting to see how slender it looks with a few hundred tons
of concrete busway on top of it.

coupled with the fact that it would have provided a useful diversion
route for the ECML.

Single track and non-electrified (ignoring the reverse at Huntingdon for
a moment) does not make a very useful diversion.

If the line had been re-opened electrifying it would have been the only
sensible option unless DMUs were to be run all the way from london or have a
DMU shuttle service from cambridge.

B2003

In article , (Roland
Perry) wrote:

In message , at
03:52:01 on Tue, 26 Apr 2011, remarked:

Given that we were told that it had "most of the track and stations
still in situ" we must conclude that the poster in question was
wanting to restore a single track railway, but it's a shame it
wasn't always next to what I think was the only remaining platforms:

http://www.disused-stations.org.uk/h/histon/histon4.jpg

Yes, a twin track busway with cycle/maintenance path is wider than
a railway, but not wider than a two-track railway and nature trail.
As far as I'm concerned the only place that width matters very much
is through bridge holes.

The nature trail isn't a part of the Cambridge-St Ives scheme. The track
was double until after passenger closure so restoring track to the
platforms could be easily incorporated in any track relaying.

The other factor overlooked is that trains only require the headroom of
single deck buses. Most buses used in Cambridge are double deck (for
capacity reasons). The Southern section of the guideway is available to
single deck buses only due to the low height of the bridges. On the
Northern section the track below bridges has had to be lowered in order
to accommodate double deckers. Luckily there aren't many bridges there
but there will be few through buses to Addenbrooke's Hospital and
Trumpington from the North because of the limitations.

And very few through[1] cast.iron trains, I expect. (another case
of comparing like with like).

[1] Even reaching Cambridge station requires using a substantial
investment from Network Rail to get from the Science Park, let
alone re-opening south towards the Trumpington P&R.

The junction is still there and was signalled, UIVMM. There are a number
of station area signalling changes needed in any case. The incremental
cost of allowing trains from St Ives in and through would be small.

I tend to agree that extending to Trumpington wasn't top priority. It is
the only bit of the busway which makes some sense, especially with the
Addenbrooke's spur.

--
Colin Rosenstiel

In message , at 06:14:20
on Tue, 26 Apr 2011, remarked:

The nature trail isn't a part of the Cambridge-St Ives scheme.

Do you mean that the trackbed had never acquired the status of a nature
trail, so apart from cyclists there's no-one that worried about it
potentially disappearing?

I took some photos of the Nottingham nature trail yesterday, not very
inspiring towards the south end. Who would believe this is the old Great
Central railway? http://www.panoramio.com/photo/51704614

That picture taken just a few yards north of the proposed Ruddington
Lane tram stop. It'll be fascinating to come back and see this in a few
years: http://www.nottinghamcity.gov.uk/net...ndler.ashx?id=
15768&p=0

It seems they've safeguarded a bridge under the A52, but Ruddington Lane
has been built on top of the embankment and will need a new bridge - but
they need new bridges over Wilford Lane and Midland Station as well.

The track was double until after passenger closure so restoring track
to the platforms could be easily incorporated in any track relaying.

Did any of the stations other than Histon have platforms left? And this
idea about relaying the track runs against assertions that a service
could be restored easily as long as the old track hadn't been "ripped
up". In reality, the old track would have been ripped up (and replaced,
even if with some of the old rails) for a railway restoration project.
--
Roland Perry

In article , (Roland
Perry) wrote:

Do you mean that the trackbed had never acquired the status of a nature
trail, so apart from cyclists there's no-one that worried about it
potentially disappearing?

It was officially a railway under engineers' possession until it was
handed over to the County Council, if you remember.

--
Colin Rosenstiel

In message , at 12:25:31
on Tue, 26 Apr 2011, remarked:
Do you mean that the trackbed had never acquired the status of a nature
trail, so apart from cyclists there's no-one that worried about it
potentially disappearing?

It was officially a railway under engineers' possession until it was
handed over to the County Council, if you remember.

There are pictures of the Ouse bridge with a tarmac path over one of the
spans (the other being derelict). So I don't think it can have been a
railway all the way. Another reason why the "use the un-ripped up old
track" issue is an oversimplification.

This at Swavesey for example: http://www.panoramio.com/photo/6784944
and a little further west: http://www.panoramio.com/photo/10391958

--
Roland Perry

In article , (Roland
Perry) wrote:

In message , at
12:25:31 on Tue, 26 Apr 2011, remarked:
Do you mean that the trackbed had never acquired the status of a
nature trail, so apart from cyclists there's no-one that worried
about it potentially disappearing?

It was officially a railway under engineers' possession until it was
handed over to the County Council, if you remember.

There are pictures of the Ouse bridge with a tarmac path over one
of the spans (the other being derelict). So I don't think it can
have been a railway all the way. Another reason why the "use the
un-ripped up old track" issue is an oversimplification.

This at Swavesey for example: http://www.panoramio.com/photo/6784944
and a little further west: http://www.panoramio.com/photo/10391958

The railway only extended to Fen Drayton by then.

--
Colin Rosenstiel

In message , at 15:04:06
on Tue, 26 Apr 2011, remarked:
It was officially a railway under engineers' possession until it was
handed over to the County Council, if you remember.

There are pictures of the Ouse bridge with a tarmac path over one
of the spans (the other being derelict). So I don't think it can
have been a railway all the way. Another reason why the "use the
un-ripped up old track" issue is an oversimplification.

This at Swavesey for example: http://www.panoramio.com/photo/6784944
and a little further west: http://www.panoramio.com/photo/10391958

The railway only extended to Fen Drayton by then.

About here then: http://www.panoramio.com/photo/4580596

Oh dear, more track that we should have stopped people ripping up, so
they could run trains on it!
--
Roland Perry

In article , (Roland
Perry) wrote:

In message , at
15:04:06 on Tue, 26 Apr 2011, remarked:
It was officially a railway under engineers' possession until it was
handed over to the County Council, if you remember.

There are pictures of the Ouse bridge with a tarmac path over one
of the spans (the other being derelict). So I don't think it can
have been a railway all the way. Another reason why the "use the
un-ripped up old track" issue is an oversimplification.

This at Swavesey for example: http://www.panoramio.com/photo/6784944
and a little further west: http://www.panoramio.com/photo/10391958

The railway only extended to Fen Drayton by then.

About here then: http://www.panoramio.com/photo/4580596

Oh dear, more track that we should have stopped people ripping up,
so they could run trains on it!

That was a railway under engineers' possession at the time.

--
Colin Rosenstiel