OT road surfaces

[Broadback]

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?

[Graham.]

Friction is not such a Bad Thing (tm) twixt tyre and road.

[Tim Lamb]

In message , Broadback writes

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!

[polygonum]

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 fuel difference.

[Tim Watts]

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 road.

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.

[Jo Stein]

...

We are now exporting one of our mountains to Netherlands in order to increase the friction on their roads:

can also send you some thorium if needed.

[Brian Gaff]

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.

Brian

[dennis]

The current idea is to have more voids. The voids are part of the drainage system to remove surface water from the motorway.

[Huge]

Lots.

[Graham.]

TRL Crowthorne.

[The Natural Philosopher]

Sadly in a car travelling at any speed developing say 30KW of power to do it the actual acoustic energy is probably less than a watt.

[newshound]

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).

[The Natural Philosopher]

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 losses.

[John Rumm]

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.

[Java Jive]

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 pr> Driving North on the M6 from Stoke there a quite a few "patches", it is

[newshound]

That's not what TRRL thought when they were helping Avon developing motorcycle tyres in the 1960s

[Jules Richardson]

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 different sounds?

cheers

Jules

[geoff]

They did experiment with a rubberised composite (made from condoms imported from the vatican city) , but it doesn't seem to have caught on

[Huge]

Please don't top post.

[bert]

Worst surface of all must be concrete. First came across it on A45 Coventry by-pass in the 60s. Thought the arse had fallen out the car Also M6 below Stafford and A50 Stoke-Uttoxeter. Hasn't got any better over the years.