Traffic noise reduction - which type of fence?

[b3taman]

Our house is well set back behind a strip of woodland from a busy road but we want to put up a high fence maybe 2.4m to further screen off traffic noise from the garden.
Anyone any experience of having a fence installed for this purpose? Would a concrete panel fence be much superior to a heavy grade close boarded fence, and any ideas about comparable costs per metre?
Thanks.

 

[lasors]

Google acoustic fencing.

 

[freddiemercurystwin]

This is the kind of thing you could potentially spend tens of thousands on but make no difference.

 

[lasors]

This is the kind of thing you could potentially spend tens of thousands on but make no difference.

True dat.

How long a fence do you need? Also the further you are from the source of the noise the higher the fence needs to be to have a reasonable effect.

If you don't want to spend money on specialist stuff then choose concrete over wood. Greater mass will help reflect more sound waves.

 

[scbk]

What about an evergreen hedge?

 

[b3taman]

Thanks for the replies guys.
I want an L shaped fence running along two adjacent boundaries of the almost square plot, as the road runs at an angle across these two sides. Each side is about 30m so it's a 60m run altogether.
I'm well aware that this could be like having a bad night at the casino if I make the wrong choice. I've arranged for a long established local fencing contractor to visit next week, they do everything from close boarded up to motorway grade acoustic fencing.
Lasors - I've already been advised that the fence should run as close to the area requiring protection as possible, as you correctly say, the value of the fence diminishes rapidly the further away it's sited.
scbk - I was originally thinking of two double rows of good old leylandii, but this would mean clearing out some of the woodland to make space, and I don't really want to do this.

 

[geraldthehamster]

Our house is well set back behind a strip of woodland from a busy road but we want to put up a high fence maybe 2.4m to further screen off traffic noise from the garden.
Anyone any experience of having a fence installed for this purpose? Would a concrete panel fence be much superior to a heavy grade close boarded fence, and any ideas about comparable costs per metre?
Thanks.

From what I read when considering a similar noise issue (though on a smaller scale), I think the fence/wall does a better job the nearer it is either to the source of the noise, or to you behind it. I don't know whether concrete panels would be better than timber or not, but the key thing is that it should be a solid barrier, without gaps. I also read that planting is only likely to have much effect if you can plant multiple rows of trees or hedging, to some depth. But I don't have direct experience of doing this.

In theory you are limited to a height of 2 metres for a wall or fence anywhere on the property, under permitted development. Anything higher would need planning permission.

Cheers
Richard

 

[seege]

Considerate building schemes i've seen in the local area have had acoustic mats that I have no clue what they are made of but they look like sports hall crash mats material on the outside. They been using them around pneumatic drill sites in Tower Hamlets

If it was me I would sandwich those things in the middle of standard fence panels or similar facade and make it as high as tolerable for sunlight and building regs.

I'm a live sound engineer and love a good acoustic physics read. The height of the wall and the wavelength of sound it will block from reaching your house are proportional. The human hearing range covers sound between half an inch at the high end down to 55ft long at the low. You gonna want a REALLY big wall for silence. Best you can hope for is reducing the high frequencies and lowering the total sound pressure level at the listening position.

Your brain also has an acoustic shield against background noise that lets you focus on a conversation in a busy place, forget you live under cit airports flight path or watch the telly when you being nagged at! That will give you the best return for your cash... sound is a b***h to stop. Good luck.

 

[b3taman]

Thanks Richard, and seege.
Richard, I am aware of the 2m PD limit, may try to push this a bit as the site is completely hidden from neighbours etc.
Seege, what you say is interesting re wavelengths. I imagine trying to stop very long waves (55ft!) is the most difficult. The mats you mention are crumbed rubber.
The biggest problem we have is medium pitched tyre noise from traffic, sounds like jet planes constantly taking off in the distance. I know it's unrealistic to try and block out the occasional low rumble from heavy lorries, but the constant medium pitched tyre roar is what I'm trying to kill.
I know what you mean about your brain blocking this out, but this noise is pretty bad and fairly constant all day, and spoils what is otherwise a great site.

 

[geraldthehamster]

.
I know what you mean about your brain blocking this out, but this noise is pretty bad and fairly constant all day, and spoils what is otherwise a great site.

I sympathise.

We have a rural road right in front of our house, that is only very busy at certain times of day, with people going to and from work at a nearby industrial estate. However, what really bugs me is later in the evening, when it's fairly quiet, and I've gone to bed. I can hear the distant swish of one car a mile away up the road, and I know that before the calm returns, there will be a couple of minutes of the sound rising and falling, and briefly appearing to stop as it is blocked by the two hosues next door, before the car comes round the bend, and loudly past my house, and fades into the distance. As traffic noise goes, its nothing, but it's a source of tension for me. I've considered all sort of remedies, but at the end of the day it doesn't bother the neighbours so I think it's a matter of perception, rather than sound proofing.

I've come to the conclusion that the best cure for traffic noise is probably hypnotherapy... or moving.

It might also be worth looking at what you can do with *part* of the site. If it's a matter of having a quiet place to sit, outdoors, then making part of your property into a walled garden, where you are sitting very close behind the 9 foot wall that nobody can see (in stone, or reclaimed brick with climbing plants etc., if it was me), could cut quite a lot of the noise. I don't know how much property you have, but planting loads of trees between it and the road couldn't hurt either (I've just re-read your original post and see that you are already behind some woodland. How close to your house is the road?)

Cheers
Richard

 

[b3taman]

Thanks Richard, I feel for you and your irritating traffic noise at night - sometimes the occasional car is worse than continuous traffic. I understand what you say about a small 'noise free' area, I have considered this.

I have attached a rough site plan, not to scale. I would guess that my house is 30m from the road. I'm surprised at how much noise seems to go straight through the woodland, although it is fairly lightly wooded.
Fencing contractor is visiting tomorrow, I'll be interested to hear his opinion. Doubtless it will involve lots of money

Siteplan

• b3taman
• 6 Aug 2013
• 1

Road noise barrier shown in red

 

[b3taman]

Sorry, just to clarify, on the previous siteplan the proposed fence is shown in red

 

[geraldthehamster]

Thanks Richard, I feel for you and your irritating traffic noise at night - sometimes the occasional car is worse than continuous traffic. I understand what you say about a small 'noise free' area, I have considered this.

I have attached a rough site plan, not to scale. I would guess that my house is 30m from the road. I'm surprised at how much noise seems to go straight through the woodland, although it is fairly lightly wooded.
Fencing contractor is visiting tomorrow, I'll be interested to hear his opinion. Doubtless it will involve lots of money

Siteplan

• b3taman
• 6 Aug 2013
• 1

Road noise barrier shown in red

Is the woodland yours? I would start by putting a fence/wall as close to road as I was able.

Cheers
Richard

 

[seege]

The woodland won't do much, to be fair. especially if it's light. If you can see through it you can definately hear through it. They will give some very slight degree of diffusion.

Noise from traffic is a summation of loads and loads of different frequencies. conversly a flute has few harmonics above a fundamental frequency. a sine wave (sounding similar to a flute, ringing in your ears or the sound with the girl with a chalk board on the telly before broadcasting kicks in in the morning, pre digital switchover) is the building block of all sound. a cymbal has many sine waves over it's fundamental frequency meaning its hard to denote a pitch. its more like white noise/static/traffic which covers the whole audible spectrum. The reason you are hearing the mid range most strongly is because this is where the ear is most sensitive. you're talking around the 1khz to 6khz region.

Low frequencies are more subject to diffraction, a phenomenon of wave motion that causes them to bend around a precepice or barrier. Thats the main reason that you will find it hard to remove them. Similar to standing in the shadow cast by a wall in the 11am sun, you are in an acoustic shadow when close to the wall and out of the shadow when you step away from it. This is why richard has advised that the wall should be close to you or the source or both.

There's a 12ft wall that separates my neighbourhood from the A12 and a footbridge that crosses it. Makes for an interesting real life example if you can find anything similar to you. just listen to how the sound changes from the bottom at street level as you walk up the steps onto the footbridge.

Essentially short of building your listening position into a soundproofed floating box the best you can realistically hope for is to this effect... make a recording of the traffic, play it through your hifi and leaving the volume the same, turn down the high eq and knock back a little of the mid.

Rule of thumb would say, Big is good - height and width, as it will lower the threshold at which sound diffracts (starting at the top of your hearing range and working down) Hard and heavy is good as it will reflect higher frequencies better. suspended helps as the absorbtion will be greater at lower frequencies if there is a bit of give in the barrier. lastly layers work well as sound loses energy when it crosses mediums and the layers if fixed firmly to each other stops the wall vibrating so much like a drum skin.

Take from all that what you will and i hope you manage to get a significant enough reduction to be satisfied with the fruits of your labour.

 

[geraldthehamster]

Take from all that what you will and i hope you manage to get a significant enough reduction to be satisfied with the fruits of your labour.

And I'd be very interested in hearing what your fencing contractor says, what you do and how well it works

Cheers
Richard