Driving North on the M6 from Stoke there a quite a few "patches", it is
very noticeable the difference in road noise when driving over the
differing surfaces. Now logic tells me that noise must use energy to be
created, therefore there must be a waste from the noisier surfaces,
whether this is in fuel efficiency or tyre wear of both I do not know.
Though it may be extremely small multiply that by the number of vehicles
and distance travelled it must significant. How much research is done on
road surfaces, apart from energy waste it has a significant effect on
people who live near busy roads?
Remember the early bird may catch the worm but the second mouse gets the
We are now exporting one of our mountains to Netherlands
in order to increase the friction on their roads:
We can also send you some thorium if needed.
"My views have changed because nuclear energy is the only
Low noise *tarmac* exists. Something about less voids minimising tyre
noise. *king expensive I expect.
Living near the elevated section of a busy commuter road, I investigated
the cost of the fencing they were erecting where the M1 passes through
Luton. Something like 6million for a few miles!
I recall an OU program from the 70's where they were looking at road
noise and reduction thereof. One solution suggested was a slightly
porous surface that reduced the air pressure shock wave created by the
rolling tyre that normally compresses air against the road.
IIRC there was a downside to the road surface in question that meant it
could only be built with a particularly hard aggregate.
But what you are hearing is a fraction of the energy transferred into
the air. Biased by your ability to hear/perceive at different
frequencies, interaction with your radio, attenuation by the vehicle,
directed in various directions, etc.
There might be a direct association between what you hear and energy
"losses" but I doubt it is simple and straightforward to establish.
Near me we have a stretch of porous asphalt motorway - and the
difference is very noticeable. But I am not convinced that there is any
Saw a programme on this years ago.
Most of the tyre noise comes from pnematic hammering as the tyre traps,
compresses and explosively releases pockets of air between itself and the
They've been experimenting with pourous road toppings fro some years now.
Pourous is good for noise reduction and also safer as it tends to drain
water away quicker avoiding sheets of standing water.
Apparantly the problems with the early attempts is the voids get silted up
and stop working. Looking at more recent efforts, I wonder if they just try
to get a layer of stones on the top with voidways between them - silt will
tend to be washed sideways and out - no real need to actually make the whole
layer porous as in earlier efforts.
Tim Watts Personal Blog: http://www.dionic.net/tim /
"A fanatic is one who can't change his mind and won't change the subject."
Have you considered that you may merely be hearing one road surface over
another due to the other one being damped out in the vehicle so the energy
waste might in one case be audible but in the other not so audible being
disapated as heat in the suspension or tyre.
From the Sofa of Brian Gaff Reply address is active
"Broadback" < firstname.lastname@example.org> wrote in message
A more extreme example is a large passenger plane coming in to land.
It's dissipating around 20MW into the air as it slows and loses
height. The amazing thing is how quiet they are (the sound energy
given off is a minute proportion of that).
[email address is not usable -- followup in the newsgroup]
You don't need much energy to produce a lot of noise. Apart from the
fact that the roughness helps with draining and avoiding the generation
of a hydrodynamic film (aka aquaplaning) the hysteresis losses in the
tyre rubber caused by deformation contribute to the friction/traction
coefficient (which helps with cornering and braking).
No: hysteresis loses do not contribute to that: they do contribute a bit
of spring damping tho so the wheel has less tendency to bounce. But
nothing like as much as the damper does.
Friction between tyre and road has very little do with with hysteresis
(in-ep-toc’-ra-cy) – a system of government where the least capable to
I've been driving around the UK a lot in the last few months looking
at houses, and I've noticed that many of the surfaces, even on major
motorways, are appallingly noisy - so noisy that there is almost no
point in having the stereo on. I'm sure the surfaces when I first
learnt to drive were nothing like as bad.
Around here, it's very noticeable that there is a mix of surfaces.
Some are newly, or relatively so, completely relaid by a proper
machine, and are very quiet, while others are very old, and seem to
date from that period in the 80s when resurfacing a road consisted of
pouring tar over it and letting hardcore/grit fall in a steady stream
from the slightly opened tailgate of a tipped up lorry reversing after
the tar lorry. If you were REALLY lucky, they might actually have
rolled it, but this was very rare. These surfaces are now universally
appalling - full of potholes, patches of bare tar that might be
slippery in unfavourable conditions, and deafeningly noisy.
On Wed, 19 Dec 2012 11:54:14 +0000, Broadback
Please always reply to ng as the email in this post's
On Wed, 19 Dec 2012 11:54:14 +0000, Broadback wrote:
There's a road I go down very occasionally which plays a tune
(deliberately) due to the surface. Ovbiously the timing is done by the
spacing of the cuts in the road surface, but I'm not sure how they change
the frequency of the notes; possibly different patterns of cuts produce
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