Discussion
What is the score with that quiet tarmac? My car feels like it's brand new and the noise from outside of passing traffic almost disappears as well. Why isn't every road completely paved with that? Is it only good for a short time after it has been put down and that's why it isn't everywhere or is there some other reason.
It's only quiet when relatively new, once the surface becomes worn it makes the same amount of noise as regular tarmac. It's also susceptible to frost and ice breaking it up as the noise suppression comes from it being porous so the water can get in it and split it apart as it freezes . It's also very draggy so will put your fuel consumption up. It has it's place but it's not suitable for everywhere.
Price has a large part to do with it and LA budgets can't run to having it everywhere, depending on who's adopted/owns the road of course.
But for fast motorways / dual carriageways near built up areas it's ideal.
I'm unsure if it's still readily available but it used to be.
Leading from that is the DOT insufferable claim of keeping with "black-top" as opposed to concrete carriageways. Some trial sections of concrete - where still in use, M1 near Watford for example and the A12 if I recall correctly, have been scarified or planed to increase life expectancy.
This practice, widely used in the US for example, both increases the life of the carriageway, and, depending on the blades/specification used, can reduce the running surface noise appreciably. Unfortunately the lobbying by the "black-top" marketeers over the years has led the concrete carriageway market suppliers ie concrete producers, to look elsewhere.
Its been some years since the last concrete carriageway was laid which in turn reduced the ability to supply and install via concrete pavers etc.
Every time I hear of an accident where the roads closed due to chemical or fuel spillages my thoughts always go back to thinking " well if that were a concrete carriageway......?"
where's that axe, I need to grind it some more......
But for fast motorways / dual carriageways near built up areas it's ideal.
I'm unsure if it's still readily available but it used to be.
Leading from that is the DOT insufferable claim of keeping with "black-top" as opposed to concrete carriageways. Some trial sections of concrete - where still in use, M1 near Watford for example and the A12 if I recall correctly, have been scarified or planed to increase life expectancy.
This practice, widely used in the US for example, both increases the life of the carriageway, and, depending on the blades/specification used, can reduce the running surface noise appreciably. Unfortunately the lobbying by the "black-top" marketeers over the years has led the concrete carriageway market suppliers ie concrete producers, to look elsewhere.
Its been some years since the last concrete carriageway was laid which in turn reduced the ability to supply and install via concrete pavers etc.
Every time I hear of an accident where the roads closed due to chemical or fuel spillages my thoughts always go back to thinking " well if that were a concrete carriageway......?"
where's that axe, I need to grind it some more......
Lord Pork said:
Price has a large part to do with it and LA budgets can't run to having it everywhere, depending on who's adopted/owns the road of course.
But for fast motorways / dual carriageways near built up areas it's ideal.
I'm unsure if it's still readily available but it used to be.
Leading from that is the DOT insufferable claim of keeping with "black-top" as opposed to concrete carriageways. Some trial sections of concrete - where still in use, M1 near Watford for example and the A12 if I recall correctly, have been scarified or planed to increase life expectancy.
This practice, widely used in the US for example, both increases the life of the carriageway, and, depending on the blades/specification used, can reduce the running surface noise appreciably. Unfortunately the lobbying by the "black-top" marketeers over the years has led the concrete carriageway market suppliers ie concrete producers, to look elsewhere.
Its been some years since the last concrete carriageway was laid which in turn reduced the ability to supply and install via concrete pavers etc.
Every time I hear of an accident where the roads closed due to chemical or fuel spillages my thoughts always go back to thinking " well if that were a concrete carriageway......?"
where's that axe, I need to grind it some more......
The concrete surface on the A4232 meant it was dubbed the "noisy" road. Are expansion joints avoidable?But for fast motorways / dual carriageways near built up areas it's ideal.
I'm unsure if it's still readily available but it used to be.
Leading from that is the DOT insufferable claim of keeping with "black-top" as opposed to concrete carriageways. Some trial sections of concrete - where still in use, M1 near Watford for example and the A12 if I recall correctly, have been scarified or planed to increase life expectancy.
This practice, widely used in the US for example, both increases the life of the carriageway, and, depending on the blades/specification used, can reduce the running surface noise appreciably. Unfortunately the lobbying by the "black-top" marketeers over the years has led the concrete carriageway market suppliers ie concrete producers, to look elsewhere.
Its been some years since the last concrete carriageway was laid which in turn reduced the ability to supply and install via concrete pavers etc.
Every time I hear of an accident where the roads closed due to chemical or fuel spillages my thoughts always go back to thinking " well if that were a concrete carriageway......?"
where's that axe, I need to grind it some more......
Evanivitch said:
The concrete surface on the A4232 meant it was dubbed the "noisy" road. Are expansion joints avoidable?
Continuously Reinforced Concrete Pavements, generally, do away with expansion joints. However, being a concrete surface it will still be loud.The UK trialled 'whisper' concrete many years ago. I was involved in the project that laid it on the A449 between Usk and the M4. It was certainly significantly quieter than a traditional concrete road but never caught on. I seem to recall there is (or was) a trial section on the M18 of various types of concrete pavement to allow a direct comparison to be made.
Most areas of concrete road have now been overlaid with a thin (asphalt) surface course to reduce noise. That's typically a Stone Mastic Asphalt, which I assume is what the OP was originally making reference to.
It's worth noting that road noise is a result of air trapped by the tyres and the road surface escaping. The smooth (brushed) finish of a concrete pavement traps more air due to its lack of surface texture, hence being louder.
Road surface noise is a function of two factors, the amount that the roughness of the surface vibrates the tyre tread blocks and the ability of the surface to absorb that noise. Surfaces with positive texture, ie a flat surface with points sticking up like spray and chip tend to vibrate the tread blocks more and be poor at absorbing noise.
SMA or thin surface course materials are more modern and are thought of as being a flat surface with holes in it. These don’t generate a lot of noise and are quite good at absorbing that noise. As mentioned above, porous asphalt is particularly quiet because it’s got lots of holes in the surface, around 20% voids and so absorbs noise well. Unfortunately the high void content means it isn’t very durable, hence it’s not often used.
We can design different types of asphalt to have different levels of road tyre noise and do so regularly as there’s becoming more demand for low noise surfacing where high speed roads run close to housing. Generally speaking a smaller aggregate size with high voids is the lowest noise surfacing, but this has to be traded against durability.
Concrete surfaces are generally more noisy than asphalt. They can be treated by fine milling them to add some roughness, but this tends to erode the transverse joints and increase the noise from joint slap. It was tried to increase the skid resistance on the concrete sections of the M25 but abandoned after it made the surface more noisy and the increase in skid resistance was only temporary. It is possible to make continuously reinforced, jointless concrete road with exposed aggregate surface, but these are considerably more expensive than asphalt roads and in some cases turn into an expensive long term maintenance problem.
If you look at road surfaces as you drive, you’ll often hear a change in road noise as you drive over surfaces with a different appearance.
(Yes, I am a professional tarmac spotter
)
SMA or thin surface course materials are more modern and are thought of as being a flat surface with holes in it. These don’t generate a lot of noise and are quite good at absorbing that noise. As mentioned above, porous asphalt is particularly quiet because it’s got lots of holes in the surface, around 20% voids and so absorbs noise well. Unfortunately the high void content means it isn’t very durable, hence it’s not often used.
We can design different types of asphalt to have different levels of road tyre noise and do so regularly as there’s becoming more demand for low noise surfacing where high speed roads run close to housing. Generally speaking a smaller aggregate size with high voids is the lowest noise surfacing, but this has to be traded against durability.
Concrete surfaces are generally more noisy than asphalt. They can be treated by fine milling them to add some roughness, but this tends to erode the transverse joints and increase the noise from joint slap. It was tried to increase the skid resistance on the concrete sections of the M25 but abandoned after it made the surface more noisy and the increase in skid resistance was only temporary. It is possible to make continuously reinforced, jointless concrete road with exposed aggregate surface, but these are considerably more expensive than asphalt roads and in some cases turn into an expensive long term maintenance problem.
If you look at road surfaces as you drive, you’ll often hear a change in road noise as you drive over surfaces with a different appearance.
(Yes, I am a professional tarmac spotter
)ingenieur said:
All very interesting. I hate concrete as a surface for roads. The aforementioned Surrey section of the M25 is so noisy inside the car and must make similarly increased noise outside.
M54 was the same when it was opened, stretchers of concrete that were very noisy and like glass when it rained, remember well the first time I drove down one of the concrete section’s, I pulled onto the hard shoulder as I thought I had a puncture due to the noise and vibration.Ardennes92 said:
ingenieur said:
All very interesting. I hate concrete as a surface for roads. The aforementioned Surrey section of the M25 is so noisy inside the car and must make similarly increased noise outside.
M54 was the same when it was opened, stretchers of concrete that were very noisy and like glass when it rained, remember well the first time I drove down one of the concrete section’s, I pulled onto the hard shoulder as I thought I had a puncture due to the noise and vibration.I remember cycling to Heathrow in the early 1960s and there was a stretch of road with a sign reading something like, "Experimental noise reduction road surfaces". I remember a difference in tyre noise as vehicles passed from one surface to another but after all this time I've no idea which was quietest.
I suppose it's a compromise between noise, grip, drainage, laying and repair costs and so on but in 2022 it's surprising that little obvious progress has been made.
I suppose it's a compromise between noise, grip, drainage, laying and repair costs and so on but in 2022 it's surprising that little obvious progress has been made.
Considerable progress has been made since the Road Research Laboratory trials near Heathrow. The default surface for a motorway is at least 3.5dB quieter that what was in use up to the mid 1990s. This is effectively a halving of perceived road noise.
It’s possible to make asphalt surfaces that are significantly quieter than that, to the point where if you’re not looking HGVs get disconcertingly close before you realise they’re there. It’s very noticeable how much we rely on noise to provide situational awareness of traffic, and how odd it is when we take that away with a super quiet surface.
It’s possible to make asphalt surfaces that are significantly quieter than that, to the point where if you’re not looking HGVs get disconcertingly close before you realise they’re there. It’s very noticeable how much we rely on noise to provide situational awareness of traffic, and how odd it is when we take that away with a super quiet surface.
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