On Wed, 19 Apr 2017 11:28:08 +0100
Roland Perry wrote:
In message , at 16:07:44
If you cycled in Cambridge you would have noticed a year or more ago.

I'll look more carefully next time I walk.
--

On a related cambridge note - why do some parts of the "guided" busway not
have guiderails? I don't mean the bits that cross other roads, I'm talking
about segregated sections such as the bit in Orchard Park? I'm struggling to
see the logic.

--
Spud

In message , at 12:47:02 on Wed, 19 Apr
2017, d remarked:

On a related cambridge note - why do some parts of the "guided" busway not
have guiderails?

Because the buses are guided by the kerbs. Rails only required at the
entrance to sections.
--
Roland Perry

On 2017-04-19 12:47:02 +0000, d said:

On a related cambridge note - why do some parts of the "guided" busway not
have guiderails? I don't mean the bits that cross other roads, I'm talking
about segregated sections such as the bit in Orchard Park? I'm struggling to
see the logic.

I think it's so other buses can use that bit.

Neil
--
Neil Williams
Put my first name before the @ to reply.

On 19/04/2017 13:47, d wrote:
On Wed, 19 Apr 2017 11:28:08 +0100
Roland Perry wrote:
In message , at 16:07:44
If you cycled in Cambridge you would have noticed a year or more ago.

I'll look more carefully next time I walk.
--

On a related cambridge note - why do some parts of the "guided" busway not
have guiderails? I don't mean the bits that cross other roads, I'm talking
about segregated sections such as the bit in Orchard Park? I'm struggling to
see the logic.

My understanding is that the guidance system is designed for high-speed
running on large-radius curves (i.e. on an old railway alignment), and
does not cope safely with curves below a certain radius. In order to fit
around the Orchard Park devlopment, that section of busway has a bend
which is too tight for guidance. It doesn't matter, as that section is
low-speed, and only a short distance between the junction with the main
busway and the point at which the busway ends. At both of those points
the driver has to take over the steering anyway, so doing so between
them is no great matter.

The only other significant unguided segregated section I am aware of is
the new piece between Milton Road and Cambridge North Station. This
doesn't have sharp bends, but again is short and low-speed. I would
guess that cost was the deciding factor there.


---
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In article , (Alan Grayer)
wrote:

On 19/04/2017 13:47, d wrote:
On Wed, 19 Apr 2017 11:28:08 +0100
Roland Perry wrote:
In message , at 16:07:44
If you cycled in Cambridge you would have noticed a year or more ago.

I'll look more carefully next time I walk.

On a related cambridge note - why do some parts of the "guided" busway
not have guiderails? I don't mean the bits that cross other roads, I'm
talking about segregated sections such as the bit in Orchard Park? I'm
struggling to see the logic.

My understanding is that the guidance system is designed for
high-speed running on large-radius curves (i.e. on an old railway
alignment), and does not cope safely with curves below a certain
radius. In order to fit around the Orchard Park devlopment, that
section of busway has a bend which is too tight for guidance. It
doesn't matter, as that section is low-speed, and only a short
distance between the junction with the main busway and the point at
which the busway ends. At both of those points the driver has to take
over the steering anyway, so doing so between them is no great matter.

The exception on the Orchard Park section is the stops and a short eastbound
section near Histon Road. They were built with true guideway sections. All
newer guidance is by steel strips on flat road surfaces.

The only other significant unguided segregated section I am aware of
is the new piece between Milton Road and Cambridge North Station.
This doesn't have sharp bends, but again is short and low-speed. I
would guess that cost was the deciding factor there.

This is probably true but the unguided section at Orchard Park probably and
the approach section to Cambridge North station definitely are unguided on
cost grounds.

The guideway track sections were cast at a concrete factory set up specially
for the purpose at (I think) Longstanton. Once the sections were made it was
demolished and the site is now a park and ride car park. So the cost of
making new guideway sections would be prohibitive and that's before you talk
about getting the special laying machine back on site. I'm not even sure
what happened to that.

None of the Cambridgeshire kit was used for the Luton busway which has
shorter track sections which can be laid by mobile crane. They probably
don't have a track section casting capability at Luton any more either.

--
Colin Rosenstiel

On Wed, 19 Apr 2017 16:14:24 -0500
wrote:
This is probably true but the unguided section at Orchard Park probably and
the approach section to Cambridge North station definitely are unguided on
cost grounds.

Comparing to clearing the ground, casting the concrete and moving into place,
how much extra in percentage terms would bolting a pair of steel guiderails
into place cost? It can't be that great and I'd be surprised if they didn't
recycle the old rail track to create them.

--
Spud

In message , at 08:19:03 on Thu, 20 Apr
2017, d remarked:
On Wed, 19 Apr 2017 16:14:24 -0500
wrote:
This is probably true but the unguided section at Orchard Park probably and
the approach section to Cambridge North station definitely are unguided on
cost grounds.

Comparing to clearing the ground, casting the concrete and moving into place,
how much extra in percentage terms would bolting a pair of steel guiderails
into place cost? It can't be that great and I'd be surprised if they didn't
recycle the old rail track to create them.

Isn't Colin saying they *didn't* cast concrete guided sections for
Cambridge North. In effect it must be just "a normal road, buses only".

Which has other benefits, such as not being restricted to
buses-with-guide-wheels.

See this Streetview of the somewhat ******* child. Presumably the short
length of guiderail is to prevent guided buses falling into the "car
trap". But an unguided bus could drive through the gap if done carefully
enough - a couple of inches clearance either side.

http://s0.geograph.org.uk/geophotos/...9_42dd46aa.jpg

Of course, it's an accident waiting to happen, because sooner or later a
driver will forget that the onward road isn't guided and take his hands
off the wheel. The drivers are not the sharpest tools in the box.

http://www.bbc.co.uk/news/uk-england...shire-20427214

"[Stagecoach] said it thought the driver had misjudged the entrance to
busway, causing it to leave the tracks.

The bus was left at a 45-degree angle across the entrance, before being
recovered from the scene a few hours later."

http://www.bbc.co.uk/news/uk-england...shire-21479277

"Passenger Michaela Murray said the bus she was on slowed down for
horses and another bus hit it from behind."

http://assets9.heart.co.uk/2016/27/c...ay-crash-july-
2016-1467897287-article-0.jpg

and probably the worst:

http://www.bbc.co.uk/news/uk-england...shire-35841300

"A guided bus driver who crashed near Cambridge injuring five passengers
was travelling at more than 53mph in a 30mph zone, a report concluded.

....

The "excessive speed" at a junction between one set of guide tracks and
another made it "unlikely the bus was under the driver's control".

--
Roland Perry

In message , at 09:44:24 on Thu, 20 Apr
2017, Roland Perry remarked:

See this Streetview of the somewhat ******* child.

If I'd pasted it in!

https://goo.gl/maps/HBDgRgXMfkn


--
Roland Perry

In article , (Roland Perry)
wrote:

In message , at 08:19:03 on Thu, 20 Apr
2017, d remarked:
On Wed, 19 Apr 2017 16:14:24 -0500
wrote:
This is probably true but the unguided section at Orchard Park probably
and the approach section to Cambridge North station definitely are
unguided on cost grounds.

Comparing to clearing the ground, casting the concrete and moving into
place, how much extra in percentage terms would bolting a pair of steel
guiderails into place cost? It can't be that great and I'd be surprised
if they didn't recycle the old rail track to create them.

I suggest you come to Cambridge and have a closer look at Guided Busway
construction. You wouldn't then spout that nonsense.

Isn't Colin saying they *didn't* cast concrete guided sections for
Cambridge North. In effect it must be just "a normal road, buses
only".

Which has other benefits, such as not being restricted to
buses-with-guide-wheels.

Not so. The steel guide rails at the entrance and exit to the roadway
prevent anything other than guided buses from entering. There's a similar
arrangement controlling access from the guideway across Harrison Way at St
Ives.

See this Streetview of the somewhat ******* child. Presumably the
short length of guiderail is to prevent guided buses falling into the
"car trap". But an unguided bus could drive through the gap if done
carefully enough - a couple of inches clearance either side.

http://s0.geograph.org.uk/geophotos/...9_42dd46aa.jpg

Of course, it's an accident waiting to happen, because sooner or
later a driver will forget that the onward road isn't guided and take
his hands off the wheel. The drivers are not the sharpest tools in
the box.

Which are amongst the reasons why it's probably illegal under the ROGS
regulations.

http://www.bbc.co.uk/news/uk-england...shire-20427214

"[Stagecoach] said it thought the driver had misjudged the entrance
to busway, causing it to leave the tracks.

The bus was left at a 45-degree angle across the entrance, before
being recovered from the scene a few hours later."

http://www.bbc.co.uk/news/uk-england...shire-21479277

"Passenger Michaela Murray said the bus she was on slowed down for
horses and another bus hit it from behind."

http://assets9.heart.co.uk/2016/27/c...ay-crash-july-
2016-1467897287-article-0.jpg

and probably the worst:

http://www.bbc.co.uk/news/uk-england...shire-35841300

"A guided bus driver who crashed near Cambridge injuring five
passengers was travelling at more than 53mph in a 30mph zone, a
report concluded.

...

The "excessive speed" at a junction between one set of guide tracks
and another made it "unlikely the bus was under the driver's control".

--
Colin Rosenstiel

In message , at 13:32:46
on Thu, 20 Apr 2017, remarked:

The steel guide rails at the entrance and exit to the roadway
prevent anything other than guided buses from entering.

....

See this Streetview of the somewhat ******* child. Presumably the
short length of guiderail is to prevent guided buses falling into the
"car trap". But an unguided bus could drive through the gap if done
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
carefully enough - a couple of inches clearance either side.

http://s0.geograph.org.uk/geophotos/...9_42dd46aa.jpg

Of course, it's an accident waiting to happen, because sooner or
later a driver will forget that the onward road isn't guided and take
his hands off the wheel. The drivers are not the sharpest tools in
the box.

Which are amongst the reasons why it's probably illegal under the ROGS
regulations.

So is speeding.
--
Roland Perry