Sustrans Blues

Tony Raven <[email hidden]>

Quoted message said:

So are these streets open to all motor traffic but closed to cycles (in
which case how is it signed) or is it just they are designated
pedestrian streets with access for loading and unloading? I find it
difficult to tell from what you have written the exact status.

I find it difficult to tell the exact status from the signs, asking the
councils or even asking the police on the scene! Some are only open to
some motor traffic, whether loading or access. I'm not sure whether all
are open to all motor traffic and they're certainly not streets you'd
choose to drive along often IMO. The most common signs are the white on
blue 'Cyclists Dismount' with the black bike in red circle being common
too. What's the legal status of 'Cyclists Dismount'? There are far too
many of them on local routes, so they're widely ignored and I think
Sustrans's board commented about their overuse on NCN Route 1 here.

The actual signs are a mess of vinyls and add-on plates that seem to
change each time I look at them. I'll go take some pictures if you want,
with the possible exception of:
- Tower Street, which has one of those revolving signs that shows
'Pedestrian Street' and a no vehicles symbol for most of daylight and AIUI
'Loading/Access Only' at other times, but has a cycling prohibited sign
(black bike in red circle) on its own post a couple of metres away;
- Sedgeford Lane's east end, which I know has no signs whatsoever,
except for a cycle route sign by its junction with Tower Street; and
- Market Lane, which has a no-through-road sign at its eastern entrance,
no signs at its west end but a path built across the junction with
Tuesday Market Place.

Quoted message said:

And apologies for the suspicion but when I asked for details of Kings
Lynn and you responded with Baldock I wondered why.

Huh? I've not written anything about Baldock in this thread.
--
MJR/slef

The Luggage said:

Ian Smith said:

The Luggage said:

Ian Smith wrote:
> On 12 Jun 2006 05:02:12, The Luggage <[email hidden]> wrote:
> >
> > I've never been terribly convinced by the 'available kinetic energy'
> > argument. For example, would you rather be hit by a 2000 tonne train
> > doing 25 mph, or a 70 tonne railbus doing 75? The slower one has 3x the
> > kinetic energy, but you're far more likely to survive it.
>
> How do you know? Or are you just guessing?

I was correlating from the 20/30/40 KSI figures regularly quoted for
cars on info ads.
Call it a guess if you like, but there is likely to be a moderate
similarity.

So you're assuming that the mass is not very relevant in order to
extrapolate figures to demonstrate that the mass is not very
relevant? (There aren't many 2000 tonne cars on the roads).

No, I'm using data that only quote the speed of the vehicle rather than
its KE or type, to show that mass is less relevant than speed.

No, you're using data serived from one particular category of vehicle
- namely road-going vehicles, which have a mass of less than (about)
40 tonnes, and assuming that the data holds valid for all categories
of vehicle, including 2000 tonne trains. That is, your data DOES
quote type, implicitly - road-going vehicles, not 2000 tonne ones.

You _are_ extrapolating way outside teh data - it may be that if the
mass of your vehicles are within an order of magnitude or so the speed
is a good indicator of lethality - but to extrapolate that the same
must hold so if you put another two orders of magnitude on the mass is
just crazy.

Quoted message said:

that KSI stats are much more strongly correlated with vehicle speed
than vehicle type, which would also support my position.

Quiote possibly, when teh vehicles in question are specifically
limited to a very narrow class of vehicle - being road-going ones.
You are doing exactly waht I said - assuming teh mass makes no
significant difference, because it (apparently) makes no significant
difference in a very narrow sub-set of data.

regards, Ian SMith
--
|\ /| no .sig
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Ian Smith said:

On 12 Jun 2006 08:49:23 -0700, The Luggage <[email hidden]> wrote:

[snip]

Quoted message said:

No, you're using data serived from one particular category of vehicle
- namely road-going vehicles, which have a mass of less than (about)
40 tonnes, and assuming that the data holds valid for all categories
of vehicle, including 2000 tonne trains. That is, your data DOES
quote type, implicitly - road-going vehicles, not 2000 tonne ones.

JOOI, are we having this discussion to score pedant points, or do you
really believe that a person is less likely to survive a 25 mph hit
from a goods train than a 75 mph hit from a railbus?

TL

The Luggage said:

Ian Smith said:

On 12 Jun 2006 08:49:23 -0700, The Luggage <[email hidden]> wrote:

[snip]

Quoted message said:

No, you're using data serived from one particular category of vehicle
- namely road-going vehicles, which have a mass of less than (about)
40 tonnes, and assuming that the data holds valid for all categories
of vehicle, including 2000 tonne trains. That is, your data DOES
quote type, implicitly - road-going vehicles, not 2000 tonne ones.

JOOI, are we having this discussion to score pedant points, or do you
really believe that a person is less likely to survive a 25 mph hit
from a goods train than a 75 mph hit from a railbus?

I think it is not obvious which is 'more likely' to kill you - I would
guess that you are almost certain to be killed by either. However,
you seem to believe it obvious that one is more lethal, and I'm
intersted to determine why.

So far, it seems to be because you're extrapolating wildly from
inappropriate data (specifically, extrapolating two orders of
magnitude outside teh available figures for the parameter under
question when the data available covers only about one order of
magnitude). If that is the sole basis for your assertions, I can
confidently regard your opinion as worthless. However, if there had
been (or indeed, still is) some other basis behind your assumptions,
it would have been interesting.

regards, Ian SMith
--
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|o o|
|/ \|

Ian Smith said:

The Luggage said:

Ian Smith said:

On 12 Jun 2006 08:49:23 -0700, The Luggage <[email hidden]> wrote:

[snip]

Quoted message said:

No, you're using data serived from one particular category of vehicle
- namely road-going vehicles, which have a mass of less than (about)
40 tonnes, and assuming that the data holds valid for all categories
of vehicle, including 2000 tonne trains. That is, your data DOES
quote type, implicitly - road-going vehicles, not 2000 tonne ones.

JOOI, are we having this discussion to score pedant points, or do you
really believe that a person is less likely to survive a 25 mph hit
from a goods train than a 75 mph hit from a railbus?

I think it is not obvious which is 'more likely' to kill you - I would
guess that you are almost certain to be killed by either. However,
you seem to believe it obvious that one is more lethal, and I'm
intersted to determine why.

Fairy nuff.
There are two parts to my argument. The first is that plenty of people
survive impacts with objects at 25 mph. Whether that object is a wall,
bus, car or train is largely irrelevant. I only put the train in
because it was easier to disprove the effect of mass (and kinetic
energy) when the mass could be increased by a factor of 30.

The second is the effect of momentum and energy tranfser I mentioned in
an earlier post. If you are hit by a vehicle that is significantly
heavier than you, the vehicle's velocity will not change much (the
momentum bit). The energy transferred to you will only be enough to
accelerate you to the velocity of the vehicle, regardless of how much
KE the vehicle has to start with.

Therefore for the train example, if you're hit by the goods train at 25
mph, a 100kg person will receive 6.23 kJ of energy in the impact. The
same preson hit by a railbus at 75 mph will have to absorb 56 kJ of
energy. Which of these is more surviveable? The 6.25 kJ impact from the
goods train, despite the fact that it has 3x more initial KE, which is
where we started.

Even at 10 mph, the goods train has more KE, and is highly likely to be
more surviveable than the 75 mph impact.

Quoted message said:

So far, it seems to be because you're extrapolating wildly from
inappropriate data (specifically, extrapolating two orders of
magnitude outside teh available figures for the parameter under
question when the data available covers only about one order of
magnitude). If that is the sole basis for your assertions, I can
confidently regard your opinion as worthless. However, if there had
been (or indeed, still is) some other basis behind your assumptions,
it would have been interesting.

The most important factors in whether you will be killed by an impact
are the speed of impact, and possibly the shape of the object you're
being hit by, not the mass or KE of the object. I don't consider the
flat front of a train to be significantly different to the flat front
of a bus or lorry, and plenty of people (though not all of course)
survive being hit by them at <30 mph

I'd already pointed to my other posts on the subject of momentum and
energy transfer, but have gone back through it above to show that there
is a sound mathematical reasoning behind by assertions.

TL

In article <[email hidden]>, Tony Raven (junk@raven-

family.com) said:

It does in a unit system. Simon is suggesting if you measured outside a
unit system e.g. the energy in joules, the mass in pounds and the
velocity in furlongs per fortnight, you would need a different constant.
Whereas most physicists would suggest the energy is 1/2mv^2 with the
energy in the pound, furlong, fortnight units system and you then need
to separately convert the answer in pound furlongs squared per fortnight
squared into joules.

Pound? POUND?? What's wrong with the good old firkin for the unit of
mass?

--
Dave Larrington - <http://www.legslarry.beerdrinkers.co.uk/>
There ought to be a /La/ against it.

The Luggage said:

The most important factors in whether you will be killed by an impact
are the speed of impact

Where the striking object is significantly more massive than you, I
think you're right (a midge hitting me at 50 doesn't concern me much).
But taking things back to "is this okay on a bike?", we're not
significantly more massive than folk we hit.

Quoted message said:

and possibly the shape of the object you're
being hit by, not the mass or KE of the object. I don't consider the
flat front of a train to be significantly different to the flat front
of a bus or lorry, and plenty of people (though not all of course)
survive being hit by them at <30 mph

True, but what happens /after/ one is initially hit is another factor.
If I get knocked over by a truck I don't have 40 sets of bogeys attached
to 100 tonne freight wagons to finish the job with basically nothing the
driver can do about it. Unless one is knocked aside by a train, that
will pretty much be it, even at 10 mph and surviving the initial impact.

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net [email hidden] http://www.dundee.ac.uk/~pjclinch/

in message <[email hidden]>, The

Luggage (') said:

Ian Smith said:

On 12 Jun 2006 08:49:23 -0700, The Luggage <[email hidden]>
wrote:

[snip]

Quoted message said:

No, you're using data serived from one particular category of vehicle
- namely road-going vehicles, which have a mass of less than (about)
40 tonnes, and assuming that the data holds valid for all categories
of vehicle, including 2000 tonne trains. That is, your data DOES
quote type, implicitly - road-going vehicles, not 2000 tonne ones.

JOOI, are we having this discussion to score pedant points, or do you
really believe that a person is less likely to survive a 25 mph hit
from a goods train than a 75 mph hit from a railbus?

Equally likely, I would have thought. Although with the railbus there
might be something recognisable to put in the coffin.

--
[email hidden] (Simon Brooke) http://www.jasmine.org.uk/~simon/

Anagram: I'm soon broke.

Dave Larrington said:

Pound? POUND?? What's wrong with the good old firkin for the unit of
mass?

Shirley you've heard lots of people use the phrase "No Firkin - Good"

--
Tony

"Anyone who conducts an argument by appealing to authority is not using
his intelligence; he is just using his memory."
- Leonardo da Vinci

The Luggage said:

Ian Smith said:

The Luggage said:

JOOI, are we having this discussion to score pedant points, or do you
really believe that a person is less likely to survive a 25 mph hit
from a goods train than a 75 mph hit from a railbus?

I think it is not obvious which is 'more likely' to kill you - I would
guess that you are almost certain to be killed by either. However,
you seem to believe it obvious that one is more lethal, and I'm
intersted to determine why.

Fairy nuff.
There are two parts to my argument. The first is that plenty of people
survive impacts with objects at 25 mph.

I have frequently survived impacts with objects well above 25mph. I'm
not sure I see how this influences any conclusions.

Quoted message said:

The second is the effect of momentum and energy tranfser I mentioned in
an earlier post. If you are hit by a vehicle that is significantly
heavier than you, the vehicle's velocity will not change much (the
momentum bit). The energy transferred to you will only be enough to
accelerate you to the velocity of the vehicle, regardless of how much
KE the vehicle has to start with.

Yes, I followed that argument, and as far as it goes, it seems
coherent. If that's your reasoning, fine (though incomplete, I
think), it was the claim that you were basing your conclusion on
extrapolating from the road ksi figures that I thought was nonsense.

Quoted message said:

The most important factors in whether you will be killed by an impact
are the speed of impact, and possibly the shape of the object you're
being hit by, not the mass or KE of the object.

Not so - the relative masses are critically important. Put your head
near the open window of a car travelling at the speed limit on a
motorway and you're bombarded with thousands (millions?) of objects of
all sorts of shapes, at relatively high speed. However, because the
mass of a dust particle is small, it does not harm you.

It would be more plausible to say that if the masses of the objects in
collision are greatly different, the damage is limited by the mass of
the lighter object. However, that would tend to support the notion
that cyclists should not be subject to the speed limits that cars are
- because cyclists are not dramatically different mass to people
(there are a lot of people that weigh more than me plus my bike).

That is, cyclists would fall into the range where KE may be the
governing factor, and their KE is relatively small, but motor vehicles
generally fall outside the range where KE is significant, so it's
reasonable to limit them by speed, not KE.

The other aspect you're neglecting is any measure of the avoidability
of an accident - even if it is the case that an impact with the 25mph
train is more survivable than the 75mph bus, the bus has a better
chance of stopping before impact than the train does. In this case, I
would expect mass is significant, and this situation does influence
the risk to bystanders of death due to impact.

regards, Ian SMith
--
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Dave Larrington said:

Pound? POUND?? What's wrong with the good old firkin for the unit of
mass?

Isn't the firkin a unit of volume? A bit like the hogshead or pin, etc. etc?
--
Chris

Rob Morley said:

In article <[email hidden]>
Jim Price <[email hidden]> wrote:
<snip>

Quoted message said:

I thought the 0.5 factor emerged from the derivation of the KE formula
where you integrate F=MA over time. A is distance per second squared and
when integrated gives 0.5 * V^2.

I was going to say something like that, but it's soooooooo long since I
did any calculus I thought it was better to have a cup of tea instead.

A very sensible idea.

http://www.nicecupofteaandasitdown.com/

:-)
--
Chris

Tony Raven said:

But all units can be defined from just three independent units. So as
soon as you have defined, for example, the three standards of mass,
length and time, all the others are defined automatically.

I'd be intrigued to see how you measure charge using only kg, m, s?
AFAIAA, only the mol is potentially redundant in the fundamental SI
units. cd might be but I don't know enough about how it is defined or
measured to know whether it could potentially be derived from black
body radiation, i.e. kg, m, s and K. (I would guess not because I don't
see how this could be extrapolated to, say, a monochromatic light
source)

Quantum mechanics throws in a whole new set of units that while
quantized (e.g. spin) also appear to be fundamental. (charge is also
suspected to be quantized and some effort has been spent in trying to
detect the magnetic monopole, the existance of which would require
charge (and magnetism) to be quantized according to current theory)

Physicists chop and change units all the time.

The most common unit changes I can think off right now are c=1
(dimensionless) and
1/4 pi epsilon0 = 1 (again dimensionless) (where the terms on the left
are assumed to have their normal SI interpretation)

Depending on which cgs system an author is using factors of 4pi can
appear and disappear seemingly at random. (No, I never did get on very
well with EM :-) )

Other places where you can have fun are for example, considering the
temperature of a diamagnetic material in an applied field. At absolute
zero all the dipoles line up, as temperature increases the dipoles
randomize until at inifinite temperature they are completely randomly
arranged.

Instead of heating, if you rapidly flip the magnetic field the dipoles
will "cool" though the infinite temperature. So if you want to use this
as your temperature scale you really need to shift the origin.

Of course, the temperature standard is set by reference to an ideal gas
and I don't know of anybody who actually talks about the "temperature"
of thermodynamically "impossible" states. But such thermodynamically
impossible states do occur (e.g. in a laser) where talking about
temperature in its SI sense becomes meaningless.

Tim.

In article said:

Tony Raven said:

But all units can be defined from just three independent units. So as
soon as you have defined, for example, the three standards of mass,
length and time, all the others are defined automatically.

I'd be intrigued to see how you measure charge using only kg, m, s?

Define the amp in terms of force between infinitely long parallel
conductors in vacuum, and then the coulomb as an amp-second, IIRC.
(That's not really how it's _measured_, but I think it's how it
was defined when I did physics A-level.)
Checking http://en.wikipedia.org/wiki/Ampere, I appear to have
remembered correctly.

Alan Braggins said:

Define the amp in terms of force between infinitely long parallel
conductors in vacuum, and then the coulomb as an amp-second, IIRC.
(That's not really how it's _measured_, but I think it's how it
was defined when I did physics A-level.)
Checking http://en.wikipedia.org/wiki/Ampere, I appear to have
remembered correctly.

oops! Yes.

I knew there were 4 pi factors in there somewhere, and, of course, this
is exactly where they come from.

Tim.

In article <[email hidden]>, Chris Slade ([email hidden])

Quoted message said:

Dave Larrington said:

Pound? POUND?? What's wrong with the good old firkin for the unit of
mass?

Isn't the firkin a unit of volume? A bit like the hogshead or pin, etc. etc?

Indeed, but I think that in the FFF system, the Firkin is defined as the
/mass/ of a Firkin of, presumably, BEER of some specified OG :-)

--
Dave Larrington - <http://www.legslarry.beerdrinkers.co.uk/>
Never give a gun to ducks.

In [email hidden] , Dave Larrington wrote
this, allegedly :

Quoted message said:

In article <[email hidden]>, Chris Slade ([email hidden])

Quoted message said:

Dave Larrington said:

Pound? POUND?? What's wrong with the good old firkin for the unit
of mass?

Isn't the firkin a unit of volume? A bit like the hogshead or pin,
etc. etc?

Indeed, but I think that in the FFF system, the Firkin is defined as
the /mass/ of a Firkin of, presumably, BEER of some specified OG :-)

I think Sir will find that the system of units he's struggling for is known
as CFF. Hundredweight/furlong/fortnights.

--
Posted via a free Usenet account from http://www.teranews.com

Tony Raven <[email hidden]> wrote: [some messages earlier]

Quoted message said:

Kings Lynn is home to one of the crappiest bit of Sustran route I've
come across. Its here:
http://maps.google.co.uk/?ll=52.774836,0.431728&spn=0.011838,0.041971&om=1
and involves crossing a side road near its junction with a main road,
doing a sharp left on onto the pavement and then an immediate sharp
blind narrow right into a concrete bollard. The person who designed it
must have been two wheels short of a bicycle.

[...]

Quoted message said:

Last summer. The problem is here:
http://makeashorterlink.com/?Q27632D3D on the turn off Hall Lane down
the alleyway.

There is a white concrete bollard on the outside of the bend. It's
nothing like blind into it. Maybe there was another one on the inside
of the bend too and it has been removed since your visit but the track
surface didn't suggest that to me.

In mitigation:
1. the alley is narrower in the middle than at the ends, so if the ends
weren't narrowed with bollards, some trailers, recumbants and so on
would get stuck in the middle;
2. the alley beside the church is a low-speed alternative to using Hall
Lane and Church Lane, which is correctly marked on the OS map as NCN 1.
I think the alley may be a Sustrans "Safe Route to School" meant for
primary-schoolers on little bikes, rather than a general NCN route.
This links back to my recurring complaint that the different qualities
of cycle route aren't clearly distinguished.

Hope that explains,
--
MJR/slef

Dave Larrington said:

In article <[email hidden]>, Chris Slade ([email hidden])

Quoted message said:

Dave Larrington said:

Pound? POUND?? What's wrong with the good old firkin for the unit of
mass?

Isn't the firkin a unit of volume? A bit like the hogshead or pin, etc. etc?

Indeed, but I think that in the FFF system, the Firkin is defined as the
/mass/ of a Firkin of, presumably, BEER of some specified OG :-)

According to the bit of paper I printed out a few days ago when this
thread was going stong, the base units in the FFFF system are fortnight
(ft), furlong( fl), farad (f) and Faraday (F). The unit of mass becomes
F^2 ft^2 / (fl^2 f), or square Faradays square fortnights per
squarefurlong farad.

The nearest equivalent SI unit is the picogramme.

I don't know what it is in Firkin-masses

HTH, HAND, etc

TL