Sound walls...do they work?

[golden eagle]

I've seen them along parts of I-285 in the Atlanta area, as well as some under construction around Augusta, GA. But are they really effective at reducing the noise level while passing by residential areas?

[Duke87]

They're obviously not going to completely block the sound. They do muffle it so it isn't quite as loud, but it's still very much audible.

Of course, they also ruin the view. Who wants to stare at a concrete wall out their bedroom window? The highway's more interesting!

[Chris]

I do noise calculations (acoustical surveys) for my work. Whenever a road is constructed, widened or new development is near a road, a noise calculation have to be made by law.

Sound walls or sound barriers do reduce the sound, although not completely, and you'll need a Berlin wall to really lower noise at locations close to the roadway. I think a good noise barrier can reduce sound levels by 4 - 6 dB. The decibel scale is logaritmic, and a 3 dB increase means the sound level doubles. So a 6 dB reduction means sound levels are two times lower than without a barrier, so that's significant.

A side-effect of noise barriers is that they reflect the sound, and if you have them on both sides of the road, it may reflect and go over the sound walls.

[Truvelo]

In the UK we just have wooden fences and vegetation where a freeway runs next to houses. Sometimes an earth mound will be built to reduce the noise and visual impact from neighboring houses.

In some European countries, notably Holland, I've seen huge glass or plastic screens alongside freeways in cities. In Austria I've seen concrete ones like that below:

[ctsignguy]

That was one thing i never understood the reasoning for....in this day of tighter state budgets, why sums of money are being expended for these ugly walls instead of bridge and roadway upkeep...

Maybe it is just me, but in many (not all) instances, the highway was there first, and neighborhoods were built around the roads (mostly the suburban beltways) or had been there so many decades that people should have gotten used to it by now....I guess i looked at the barriers around newer places from a perspective of 'Hey, you CHOSE to buy an house near an Interstate, get over it!  Don't expect the taxpayers to pick up the tab or this!" 

I guess for me, the sounds of traffic on the Interstate are a siren call...gets my travel finger itchy again and i need hit the road and go somewhere....

Then i heard the Feds were requiring these silly things...true or not?

[roadfro]

That was one thing i never understood the reasoning for....in this day of tighter state budgets, why sums of money are being expended for these ugly walls instead of bridge and roadway upkeep...

Maybe it is just me, but in many (not all) instances, the highway was there first, and neighborhoods were built around the roads (mostly the suburban beltways) or had been there so many decades that people should have gotten used to it by now....I guess i looked at the barriers around newer places from a perspective of 'Hey, you CHOSE to buy an house near an Interstate, get over it!  Don't expect the taxpayers to pick up the tab or this!"
(...)
Then i heard the Feds were requiring these silly things...true or not?

Sound levels are one of the criteria evaluated during environmental impact studies. If it can be shown that freeway widening/construction will increase ambient noise levels above a certain decibel near existing neighborhoods, a soundwall has to be installed to mitigate the impacts.

Nowadays, at least in some areas, soundwalls are more aesthetically pleasing. They're using multiple colors, textures and designs on both sides of the wall so that they aren't so drab and ugly.  Certainly, this was partially due to complaints from people who had to stare at the wall from the backyards.

A story was linked in the roadgeek YahooGroup about a freeway stretch that recently opened near a neighborhood. The residents were quite unhappy when they found out the freeway was going in, but apparently they and/or the home sales reps didn't do adequate research when they bought their homes. Since the homes were constructed well after the EIS was completed, no soundwalls were built next to them.

[Scott5114]

My apartment building is on an I-35 service road. They just added a Jersey barrier as part of the widening works.

Before or after that Jersey barrier was put up, I couldn't hear a damn thing.

[Ian]

I agree with Duke87, sound barriers totally ruin the view. I would rather look at a highway than a concrete wall.

[froggie]

To elaborate on what roadfro mentioned, as a general rule, already-existing highways do not require sound walls, unless the highway undergoes a major reconstruction and/or capacity expansion...and where the environmental studies for said project identify the need for noise mitigation.

There are also some states that will install sound walls if certain criteria are met, or if those requesting the sound wall pay for it.  MnDOT, for example, has a criteria whereby if a certain number of households/businesses along a highway would experience a certain level of sound (I don't recall the specific numbers, unfortunately), they will use state funds to install a sound wall.  If the criteria aren't met, they won't...but they'll still build the sound wall if the requestors pony up the funds.


This is why you'll commonly see soundwalls being built along new or expanded highways, but none or few along already existing highways.

The story roadfro referred to involves the new opening of a stretch of I-485 outside Charlotte, NC.

[roadfro]

To elaborate on what roadfro mentioned, as a general rule, already-existing highways do not require sound walls, unless the highway undergoes a major reconstruction and/or capacity expansion...and where the environmental studies for said project identify the need for noise mitigation.

There are also some states that will install sound walls if certain criteria are met, or if those requesting the sound wall pay for it.  MnDOT, for example, has a criteria whereby if a certain number of households/businesses along a highway would experience a certain level of sound (I don't recall the specific numbers, unfortunately), they will use state funds to install a sound wall.  If the criteria aren't met, they won't...but they'll still build the sound wall if the requestors pony up the funds.

Something like this happened in Las Vegas.  I-515/US 93/US 95 southwest of downtown (between Las Vegas Blvd and Charleston Blvd/SR 159) recently had soundwalls installed.  This section was built in the early 80's, elevated through established neighborhoods.  Although the highway hasn't been expanded at all since original construction, the City of Las Vegas took the lead on building these soundwalls a few years ago--they paid for much of it through the city budget, with some grant or other funding and maybe a small amount of assistance from NevadaDOT.  The design is more aesthetically pleasing than standard NDOT walls...possibly because it wasn't an NDOT project.

NDOT has long range plans to expand this section of freeway.  Knowing this, the soundwall was designed as post-and-beam construction.  The posts will be reset and beams moved when the freeway is expanded in the future, thus not completely wasting the expense of installing the walls prior to freeway widening.

[Alps]

I live (yea) feet away from I-287, one of several busy NJ freeways.  There is a sound wall.  I hear nothing unless I walk up within 10 feet of the road.

[Terry Shea]

That was one thing i never understood the reasoning for....in this day of tighter state budgets, why sums of money are being expended for these ugly walls instead of bridge and roadway upkeep...

Maybe it is just me, but in many (not all) instances, the highway was there first, and neighborhoods were built around the roads (mostly the suburban beltways) or had been there so many decades that people should have gotten used to it by now....I guess i looked at the barriers around newer places from a perspective of 'Hey, you CHOSE to buy an house near an Interstate, get over it!  Don't expect the taxpayers to pick up the tab or this!" 

I guess for me, the sounds of traffic on the Interstate are a siren call...gets my travel finger itchy again and i need hit the road and go somewhere....

Then i heard the Feds were requiring these silly things...true or not?

I don't get it either.  I spent the weekend in Indianapolis and they're going up all over I-465.  That freeway's been there for probably 45 years or so.  There can't be very many people still living along the freeway who lived there before the freeway was built.  Anyone moving into the area should know what they're getting into (and I've lived along freeways before and had no trouble with noise at night).  But it's the same way with Ford International Airport here.  People buy homes within a mile or so of the airport and then complain and demand that the airport do something about the noise from planes flying overhead!  I don't know who's stupider; the people who buy these homes or the officials who try to appease such ignoramuses.

[mapman]

I don't know who's stupider; the people who buy these homes or the officials who try to appease such ignoramuses.

Yah, but those ignoramuses vote, and thus the politicians listen.     

[Terry Shea]

I don't know who's stupider; the people who buy these homes or the officials who try to appease such ignoramuses.

Yah, but those ignoramuses vote, and thus the politicians listen.     

Yeah, but they're probably too stupid to punch the ballot out correctly. 

[tdindy88]

To elaborate on I-465, those walls are being placed only where the highway was recently expanded, like within the last 10 years, including the current construction on the west side of 465 where they're being placed along most if not all of the stretch of the highway. I live close to I-65 on the southern part of the city and there are no plans anywhere for walls along the highways, though there are a couple of subdivisions nearby that do have a mound of dirt and grass seperating them from the highway so you don't actually see the interstate.

[hm insulators]

I myself have never understood building sound walls along freeways in older neighborhoods because people move to a house close to the freeway that was built 30 years previously, then complain about the racket! So instead of spending money to widen roadways that badly need it or new roadways that badly need to be built, the state builds these stupid sound walls instead. And then the state cries that they don't have money to solve the traffic problems.

I can understand building sound walls as part of a new highway, especially if the area around the new highway will soon be built up with subdivisions. That's another thing.

[roadfro]

When they want to widen existing freeways and the environmental study shows a negative sound impact, federal highway requirements demand a sound wall be constructed to mitigate the impact.  If the state doesn't build the soundwall where an environmental study shows one is needed, the state is likely to not get federal funding to expand the road.  Since most states can't afford to foot the entire bill on highway projects, they'll build the wall in order to ensure they get the federal funds to widen the highway.

[BigMattFromTexas]

I don't know what it's like to be in a new development with sound barriers, but i hate seeing em' because some seem way to close to the highway, plus I like to see traffic, and i like to see emergency vehicles, and other stuff like that.
BigMatt