Annabel Smyth wrote:
On Sat, 17 Jul 2004 at 14:40:32, JNugent
wrote:

And no, I am not referring temporary limit at a set of roadworks
(even though 40 is still extracting the urine a bit, even at
roadworks). I am speaking of a permanent limit of 40mph on part of
the M4.

Do you not agree that such a limit is *way too low* on a motorway?

Not on that particular section of the M4 - it does keep traffic
moving, and has enabled them to extend the 60 mph section much
farther back (it used to be 50 mph right out to Slough,
practically).

IIRC the limit (eastbound) used to be 70 until about just west of the
elevated section, then 50. When the bus lane was introduced, the limit
became 50 from junction 4 (Heathrow T123), then 40 from half a mile
before the elevated section. The 50 limit has now been raised to 60,
and still starts at j.4. I think that it was the limit from j.4 that
smoothed out the traffic flow (and not, as the government would like to
think, the bus lane).

Westbound, the 70 limit starts immediately after the elevated section,
and always has done.

--
Richard J.
(to e-mail me, swap uk and yon in address)

On Sat, 17 Jul 2004 13:57:02 GMT, "Richard J."
wrote in message
:

You're presumably referring to the elevated section of the M4 in London,
which has 2 lanes per carriageway, no hard shoulder, and very heavy
traffic flows. This is not a typical motorway, though I felt that the
previous 50mph limit here was adequate. Anyone know what the accident
rate was on this section before the 40 limit was imposed?

Dunno, but I can't recall ever achieveing such dizzying speeds on that
particuilar bit of road :-)

Guy
--
May contain traces of irony. Contents liable to settle after posting.
http://www.chapmancentral.co.uk

88% of helmet statistics are made up, 65% of them at Washington University

Velvet wrote:

JNugent wrote:

Ambrose Nankivell wrote:

[ ... ]

... If you want to discredit speed
limits, then give examples of where they're set too low or too high,
rather than criticising signing policy.

How about 40mph on the M4?
And no, I am not referring temporary limit at a set of roadworks
(even though 40 is still extracting the urine a bit, even at
roadworks). I am speaking of a permanent limit of 40mph on part of
the M4.
Do you not agree that such a limit is *way too low* on a motorway?

And exactly where is this 40mph on the M4? Perhaps where it passes
through a built up area in London, where the lanes are narrow and it
twists with frequent junctions?

I don't know what you are trying to imply, but a motorway passing through a
"built-up area" is entirely separate from the local road network. Think of
the M6/M5 in NW Birmingham, Dudley, Walsall, etc. Perhaps you think they
should be limited to 40 as well?

The Chiswick Flyover's lanes are exactly the same width as any other
motorway lanes (12' wide). It doesn't have hard shoulders, but then, neither
do a great many 2 x 2-lane d/cs limited to 70mph - so of what relevance
could that be?

As for "frequent junctions"... there is one junction (where the A4
"becomes" the M4) at the western end and one intermediate junction (with the
N & S CRs).

Let's see... that's... er... two junctions.

You'd have to be pretty weird to class that as "frequent", wouldn't you?

I drive the M4 regularly, between central london right out to Wales.
The only place I can think that such a limit exists is where you get
close to London, and there are very good reasons for the limit at that
point.

In that case, you'll have no difficulty in explaining them.

Some more information on where your 40 mph limit on the M4 would be
useful in determining whether it is justified and thus not a valid
piece of supporting evidence; or not.

Are you denying that there is a permanent 40mph limit on part of the M4?

A funny thing to do for someone who claims to drive on it regularly.


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JNugent wrote:

Velvet wrote:


JNugent wrote:


Ambrose Nankivell wrote:


[ ... ]


... If you want to discredit speed
limits, then give examples of where they're set too low or too high,
rather than criticising signing policy.


How about 40mph on the M4?
And no, I am not referring temporary limit at a set of roadworks
(even though 40 is still extracting the urine a bit, even at
roadworks). I am speaking of a permanent limit of 40mph on part of
the M4.
Do you not agree that such a limit is *way too low* on a motorway?


And exactly where is this 40mph on the M4? Perhaps where it passes
through a built up area in London, where the lanes are narrow and it
twists with frequent junctions?


I don't know what you are trying to imply, but a motorway passing through a
"built-up area" is entirely separate from the local road network. Think of
the M6/M5 in NW Birmingham, Dudley, Walsall, etc. Perhaps you think they
should be limited to 40 as well?

That depends on the local circumstances. Having also driven that
several times, I would say it is possible that it should. It can get
very busy, and have long queues in one (or more, but often one) lane as
people attempt to join/exit the motorway, with faster traffic in the
other two. I have seen nasty near misses where people attempt to queue
jump, and try and join the faster moving lanes from the queueing one,
then cut back in later on.



The Chiswick Flyover's lanes are exactly the same width as any other
motorway lanes (12' wide). It doesn't have hard shoulders, but then, neither
do a great many 2 x 2-lane d/cs limited to 70mph - so of what relevance
could that be?

Possibly the fact that it is:

a flyover. Some vehicles can end up over/through bridges and on the
road below that they span - or has this not occurred to you? I've
actually seen that happen.

no hard shoulders - on a road as busy as that, it is inevitable that
breakdowns and accidents occurr. As such, there is no way to get cars
out of the main lanes, and the impact on traffic is severe, causing
queueing, and approaching such a situation at 70 can be very dangerous,
approaching at 40 takes away some of that danger though not all.

queueing - I've seen this many many times on this stretch. Approaching
a queue at 40 is a wholly different situation to approaching a queue at
70-80, as would happen if the limit was as you appear to want it, 70.

multiple bends leading to restricted visibility - again, a valid reason
for the limit to be lowered.

short slip lanes onto and off - as you drive this, no doubt you're aware
of the short length that the slip roads parallel the main carriageways,
no? The faster the speed of the traffic on the main carriageways, the
longer the slip lane must be to avoid the problems where vehicles are
unable to merge successfully. This is, as I'm sure you're aware,
exacerbated by the fact that there are no hard shoulders in which to
utilise in this situation - you're faced with making a dead stop before
the concrete barrier gets you, or swerving out into the side/right in
front of someone at the last minute.

And as a regular driver, I'm well aware that since the limit was
lowered, there are less accidents on that stretch, and journey times are
more predictable.

Exactly which ones of the above reasons are you going to disagree with,
I wonder.


As for "frequent junctions"... there is one junction (where the A4
"becomes" the M4) at the western end and one intermediate junction (with the
N & S CRs).

Let's see... that's... er... two junctions.

You'd have to be pretty weird to class that as "frequent", wouldn't you?


Perhaps I'm thinking of further on, where it becomes the A4, but
regardless, the traffic flows better since the limit was set to 40.
Live with it.


I drive the M4 regularly, between central london right out to Wales.
The only place I can think that such a limit exists is where you get
close to London, and there are very good reasons for the limit at that
point.


In that case, you'll have no difficulty in explaining them.


Already done.

Some more information on where your 40 mph limit on the M4 would be
useful in determining whether it is justified and thus not a valid
piece of supporting evidence; or not.


Are you denying that there is a permanent 40mph limit on part of the M4?


No, please read more carefully.


A funny thing to do for someone who claims to drive on it regularly.

Indeed, but as I said, you should read more carefully, I didn't deny it,
I merely asked you to state where it was, so we could be sure we were
both talking about the same thing. To the casual reader of *your* post,
you seem to be talking about a stretch of the M4 that is 3 lanes wide
with full hard shoulders, that has the same with a 70 limit to each side
of it, admittedly this would be a little peculiar.

By omitting to state where the limit was, or give any other information
on how the road differed from the more common motorway, you appeared to
be attemping to mislead by omission.

Since you chose to use the 40 mph limit on the M4, yet omitted to state
*where* it was along the length, it was incumbent upon you to clearly
define where it is, not me.

Obviously the subtly of my post sailed completely over your head.


--


Velvet

On Sun, 18 Jul 2004 10:45:54 GMT, Velvet
wrote in message :

Exactly which ones of the above reasons are you going to disagree with,
I wonder.

You are mistaking The Nugentoid of Kager IV for a rational being. The
answer to that is probably "all of them" ;-)

Guy
--
May contain traces of irony. Contents liable to settle after posting.
http://www.chapmancentral.co.uk

88% of helmet statistics are made up, 65% of them at Washington University

Velvet wrote:

JNugent wrote:
Velvet wrote:

[ ... ]

... If you want to discredit speed
limits, then give examples of where they're set too low or too
high, rather than criticising signing policy.

How about 40mph on the M4?
And no, I am not referring temporary limit at a set of roadworks
(even though 40 is still extracting the urine a bit, even at
roadworks). I am speaking of a permanent limit of 40mph on part of
the M4.
Do you not agree that such a limit is *way too low* on a motorway?

And exactly where is this 40mph on the M4? Perhaps where it passes
through a built up area in London, where the lanes are narrow and it
twists with frequent junctions?

I don't know what you are trying to imply, but a motorway passing
through a "built-up area" is entirely separate from the local road
network. Think of the M6/M5 in NW Birmingham, Dudley, Walsall, etc.
Perhaps you think they should be limited to 40 as well?

That depends on the local circumstances. Having also driven that
several times, I would say it is possible that it should. It can get
very busy, and have long queues in one (or more, but often one) lane
as people attempt to join/exit the motorway, with faster traffic in
the other two. I have seen nasty near misses where people attempt to
queue jump, and try and join the faster moving lanes from the
queueing one, then cut back in later on.

Are you *really* saying that a 15 mile stretch of the country's premier
north/south route should have a 40mph limit?

The Chiswick Flyover's lanes are exactly the same width as any other
motorway lanes (12' wide). It doesn't have hard shoulders, but then,
neither do a great many 2 x 2-lane d/cs limited to 70mph - so of
what relevance could that be?

Possibly the fact that it is:

a flyover. Some vehicles can end up over/through bridges and on the
road below that they span - or has this not occurred to you? I've
actually seen that happen.

So do all flyovers have a 40mph limit?

Or - in your world - *should* all flyovers have a 40mph (or lower) limit?

If not, why that one (which was designed and built to have no speed limit at
all)?

no hard shoulders - on a road as busy as that, it is inevitable that
breakdowns and accidents occurr. As such, there is no way to get cars
out of the main lanes, and the impact on traffic is severe, causing
queueing, and approaching such a situation at 70 can be very
dangerous, approaching at 40 takes away some of that danger though
not all.

So should all greade-separated, motor-traffic-only, dual-carriageways
without a hard shoulder (and there are a lot of them) have a 40mph limit?

If not, why this one?

queueing - I've seen this many many times on this stretch.
Approaching a queue at 40 is a wholly different situation to
approaching a queue at 70-80, as would happen if the limit was as you
appear to want it, 70.

So, to develop your theme, you are also saying that any route subject to
queuing should have a 40mph limit?

multiple bends leading to restricted visibility - again, a valid
reason for the limit to be lowered.

The M4 does not have "multiple bends". Its alignment was designed for 70mph+
(as are all motorways of the period except for one bend on the northern
reaches of the M5).

short slip lanes onto and off - as you drive this, no doubt you're
aware of the short length that the slip roads parallel the main
carriageways, no? The faster the speed of the traffic on the main
carriageways, the longer the slip lane must be to avoid the problems
where vehicles are unable to merge successfully. This is, as I'm
sure you're aware, exacerbated by the fact that there are no hard
shoulders in which to utilise in this situation - you're faced with
making a dead stop before the concrete barrier gets you, or swerving
out into the side/right in front of someone at the last minute.

So again, any road without hard shoulders - in your view at least - must
have a 40mph limit?

Is that a fair summary of your position?

And as a regular driver, I'm well aware that since the limit was
lowered, there are less accidents on that stretch, and journey times
are more predictable.

"More predictable".

Weasel words for "predictably longer"?

Exactly which ones of the above reasons are you going to disagree
with, I wonder.

Since none of them seem to apply anywhere else (not even in Livingstone's
London - look at the [former[ A40(M) and A102(M), for instance), I wonder
how seriously you can expect any of them to be taken. And your problem is
that none of them have a logical boundary. If the 40mph limit on M4 at
Chiswick/Osterley were justified, then the same limit would be justified on
every dual two-lane d/c in the country which has no hard shoulders and is
subject to peak overload. The non-upgraded sections of the A1, for instance.
Or the A14. Or the A12, or the A10 through East Anglia.

As for "frequent junctions"... there is one junction (where the A4
"becomes" the M4) at the western end and one intermediate junction
(with the N & S CRs). Let's see... that's... er... two junctions.
You'd have to be pretty weird to class that as "frequent", wouldn't
you?

Perhaps I'm thinking of further on, where it becomes the A4,

Irrelevant.

That road has *always* had a lower limit than its motorway continuation.
Motorways have higher speed limits than urban radial routes because they are
safer at higher speeds. That is the reason why motorways (rather than mere
at-grade d/c extensions) are built.

Using your "logic", the M1 should have a 30 limit because it is an extension
of Holloway Road and Baker Street.

but
regardless, the traffic flows better since the limit was set to 40.
Live with it.

"Flows better" is a peculiar interpretation of it. It certainly flows more
slowly. I guess that for some, "slower" is automatically "better".

[ ... ]

Some more information on where your 40 mph limit on the M4 would be
useful in determining whether it is justified and thus not a valid
piece of supporting evidence; or not.

Are you denying that there is a permanent 40mph limit on part of the
M4?

No, please read more carefully.

Since you now claim to know where the 40 limit is, what was your purpose in
asking where it was?

...To the casual reader of
*your* post, you seem to be talking about a stretch of the M4 that is
3 lanes wide with full hard shoulders, that has the same with a 70
limit to each side of it, admittedly this would be a little peculiar.

No, please read more carefully.

I said nothing of the sort. I said that a stretch of M4 has a 40 limit.

And that was correct.

And (more importantly), it is an example of "...speed limits ... set too
low" - remember the orginal context?

By omitting to state where the limit was, or give any other
information on how the road differed from the more common motorway,
you appeared to be attemping to mislead by omission.

Not at all. The Chiswick section of M4 was designed and built to be operated
at no speed limit whatsoever - though it had the national 70 limit imposed
soon after opening.
Since you chose to use the 40 mph limit on the M4, yet omitted to
state *where* it was along the length, it was incumbent upon you to
clearly define where it is, not me.

What difference does it make where it is?

40 is ridiculously low for a motorway.


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In message , JNugent
writes

So do all flyovers have a 40mph limit?

Or - in your world - *should* all flyovers have a 40mph (or lower) limit?

If not, why that one (which was designed and built to have no speed limit at
all)?

See:

http://www.highways.gov.uk/news/pres...16_07_2002.htm

Notes to Editors
----------------

3. The 40mph limit on the elevated section will not be raised because
this only meets standards for a 40mph road.

--
Paul Terry

JNugent wrote:

The Chiswick section of M4 was designed and built to be
operated at no speed limit whatsoever - though it had the
national 70 limit imposed soon after opening.

You can't design a road for "no speed limit whatsoever". Britain's
motorways were generally designed for 70 mph, but it's obvious that the
first bend on the M4 going west was designed to a lower standard. I
thought the 50 mph limit on that stretch was imposed from first opening,
BICBW.

--
Richard J.
(to e-mail me, swap uk and yon in address)

"Richard J." wrote in message
...
JNugent wrote:

The Chiswick section of M4 was designed and built to be
operated at no speed limit whatsoever - though it had the
national 70 limit imposed soon after opening.

You can't design a road for "no speed limit whatsoever". Britain's

GErman Autobahns seem to throw that out of the window. Sure you can't design
a road for "no speed whatsoever", but theres no need for a limit on many
roads. At least that's what the most populous country in Euroep seems to
think.
--
Everything above is the personal opinion of the author, and nothing to do
with where he works and all that lovely disclaimery stuff.
Posted in his lunch hour too.

In message , Richard J.
writes

You can't design a road for "no speed limit whatsoever". Britain's
motorways were generally designed for 70 mph,

There was no speed limit whatsoever for the first six years ... it was
not until 1965, after reports of test drivers reaching nearly 170mph on
the M1, that a 70mph limit was introduced on motorways.

but it's obvious that the
first bend on the M4 going west was designed to a lower standard.

If you mean the Chiswick flyover, it wasn't even part of the motorway
when it was built in 1959 by Tory transport minister Ernest Marples'
construction company, Marples Ridgway - it was just a flyover on the A4.

It didn't become the most easterly part of the M4 until six years later
when, by curious turn of fate, the rest of the elevated section was
completed by chief engineer Sandy Darling, father of Alistair Darling,
and became (with Westway) the symbol of the way in which roads had been
put before homes in the 1960s.

--
Paul Terry