Skip to content
 

Austin Formula 1 Track Noise Analysis

With construction on the new Circuit of the Americas track underway in Southeast Austin after a quick approval process, some are uncertain about what benefits and detriments the track will have for the city in the long run.  Unable to find evidence of any kind of environmental or noise study, I decided to build a computer noise model of the track and the surrounding areas using SoundPLAN to investigate the potential noise exposure of the surrounding area caused by vehicles operating on the track.

These are the data and assumptions that went into the model:

  • Terrain data and image data for the area came from the National Map.  Construction of the track will result in elevation changes in certain places, especially along the track itself, but I don’t have access to that data so I had to assume the elevations would be close to existing conditions.  Long-distance propagation like this should not be highly affected by the types of elevation changes that the track area will undergo.
  • Track layout and facility building locations were taken from the posted Conceptual Master Plan at the Circuit of the Americas website.
  • The noise source was assumed to be a single open-wheel car circling the track alone.  I was unable to locate noise data for a Formula 1 vehicle, but measurement data for an IndyCar pass-by was presented by Harris, Miller, Miller & Hanson in their analysis of the Baltimore Formula 1 track.  Formula 1 and IndyCar vehicles are indeed different, but should be similar enough for the purposes of this study.  If anything, this is a conservative substitution as Formula 1 vehicles operate at more extreme parameters.
  • Facility Buildings that could provide some noise shielding, including the grandstands and maintenance buildings, were included in the model.
  • Natural Seating Areas around the track were modeled as grassy berms to provide noise shielding where they are located.

The noise model predicted the maximum level experienced based on a single trip around the track for one car.  Multiple cars in a group would, of course, be additive and would increase the predicted levels based on the number of cars according to logarithmic addition.  2 cars would be ~3 dB louder than one car, 3 cars would be ~5 dB louder than 1 car, 4 cars would be ~ 6 dB louder than one car, 5 cars would be ~7 dB louder than one car, and so on.

The results for the entire analysis area are shown below:

CotA Single Car Pass

To the West, there appear to be no real problems.  Out in the country the car on the track would be clearly audible outdoors, but probably not disturbing.  To the North, South, and East, the track is much closer to the property line and to residences.  A single car would register levels as high as the upper 80′s dBA for the closest residences, which most people would find disturbing, both indoors and outdoors.

Scanning the satellite images, I located what appear most likely to be residential structures close to the track and included them as buildings in the model.  They are shown as dark blue boxes in the figures.

On the north side of the track, the houses near the entrance can expect noise exposure from a single vehicle pass-by ranging from about 70 dBA to 80 dBA.  This would be difficult to talk over in an outdoor environment, and would be clearly audible inside of most homes (though not necessarily disturbing).  Multiple cars on the track would likely increase interior sound exposure to levels that most people would find annoying.

CotA Single Car Pass Zoomed North

To the East, the track is closer to residential buildings, so greater impacts are expected.  Noise exposure between the mid 70′s and mid 80′s dBA from a single car pass is predicted for homes in this area.  Assuming a difference of about 20 dBA outside to inside (typical for residential buildings), inside noise levels could be expected between 55 and 65 dBA for a single car.  These levels correlate to loud but normal conversation volumes, meaning that people inside these houses would need to either speak loudly or wait for a car to pass to carry on a conversation.

CotA Single Car Pass Zoomed East

Predicted noise exposure on the south side is greater still, with some buildings expected to be exposed to levels in the mid to upper 80′s dBA for a single vehicle pass.  With these exterior noise levels, it may be difficult to carry on a conversation inside of any building with ordinary construction.

CotA Single Car Pass Zoomed South

There are still other potential noise impacts to consider beyond just the sound from a single car on the track affecting residences in the area.

  • Other noise sources, such as traffic and the cheering of spectators may produce noise sufficient to disturb residents of the area.
  • Race car noise may stress or frighten livestock.
  • Noise signatures from other types of cars using the track, such as the V8 Supercars, may have lower frequency content, resulting in noise with longer carry and better ability to penetrate building structures.
  • It appears very likely that the track will be operating in exceedance of the Austin noise ordinance.
If noise problems are identified and addressed early in the design process, they can be solved before any impacts occur, during the original construction.  In most cases, it is several times more expensive to solve a noise problem through retrofit than to include mitigation in construction.  Additionally, once a noise impact on a community has already occurred, it is substantially more difficult to achieve satisfaction with the surrounding community than it would have been had the impact been avoided at the outset.
Based on the results of this analysis, and the potential for other noise impacts associated with the race track facility, a comprehensive noise analysis as part of the track’s design and construction seems like a prudent investment.  An analysis performed by an acoustical engineer could determine the necessary locations and heights of barriers and berms that would mitigate the noise impacts on nearby residences.

9 Comments

  1. [...] some data and created a SoundPLAN model of the track and area. I posted the model's results at Austin Noise. Those cars are really, really loud. This is actually a very conservative model and I would expect [...]

  2. Al Rodriguez says:

    We should do all the race fans a big favor and move if near them who love the “sport” & set it closer to them that to us who don’t need or want every aspect of it.

  3. M Ridge says:

    Interesting study but, some of your comparisons are a little suspect.

    A normal conversation is usually measured between 60-70 db, not a loud conversation at 65db.

    Also, an outdoor sound at 80db would be barely noticeable indoors with the windows shut. A typical phone dialtone registers at 80db, hardly a conversation stopper.

    A mower, 3 ft away registers at 107 db, much louder than a typical conversation but, once again, indoors, hardly noticeable.

    These homes are very close to the airport and the typical jet on takeoff can hit well over 120db.

    Don’t get me wrong, at the track, you will need hearing protection, which I use at any race but, once you get very far away, the noise will just fade out. F1 cars are typically very high pitch which fades rapidly.

    http://www.gcaudio.com/resources/howtos/loudness.html

    • The term “dB” by itself has little meaning. It needs to be qualified. The numbers on the chart you linked to are not qualified, but it appears they’re just copies of A-weighted SPL from another chart elsewhere.

      Normal conversation levels are in the 65 dBA range. If there is another, intruding noise that is also at 65 dBA, then the conversation becomes difficult to continue as there is another noise that must be talked over.

      An outdoor noise at 80 dBA would absolutely be noticeable indoors, even with the windows shut. The typical outdoor to indoor noise reduction provided by a building is 20 dBA. More for a high quality construction with sound rated windows, less for cheaper construction. In remote areas like this, construction tends to be towards the cheap side with respect to noise insulation, which is to be expected. Why spend any money on high STC windows when there aren’t any noise sources to worry about?

      A lawn mower may be 107 dBA 3 feet away. That would mean it is ~103 dBA 6 feet away, and about ~99 dBA 12 feet away. Remember that sound spreads geometrically. For race car noise from a track that is hundreds or even thousands of feet away to be greater than 80 dBA is very significant. It will be that level everywhere around a house, not just in a sphere around one machine. In other words, even with similar levels of exposure, the amount of sound energy the house is exposed to is considerably more, since all of its surface area is exposed to the same intensity.

      Even so, I would be curious to visit your house, since apparently it is built like a bomb shelter and has no windows. A lawn mower being operated in my yard is always noticeable. A lawn mower being operated in my neighbor’s yard is noticeable. This is not surprising, as I do not have STC 45 windows on my house.

      A dial tone is 80 dBA when the receiver is held up to your ear, centimeters away from the speaker. You cannot lift a receiver and produce an 80 dBA tone throughout a room, unless you have a very loud phone that would inflict permanent hearing damage on anyone who attempted to use it. Remember that sound spreads geometrically, and that distance from the source is just as significant as SPL. 3 feet from a phone the dial tone will be audible, but it will be nowhere near 80 dBA.

      A jet engine can absolute cause sound levels to exceed 120 dBA, NEAR the jet engine. Miles away sound levels are much less. Find a copy of the ABIA airport noise contours and you will see that the 65 dBA contour is far away from the Formula 1 site. Airplane noise at this location will not be comparable to race car noise for homes close to the track.

      The SoundPLAN software takes frequency into account for its noise propagation calculations. Air and ground absorption are absolutely frequency dependent, and those effects have already been accounted for in this analysis.

  4. R Webb says:

    Keep in mind that a turbocharged car with open exhaust is significantly quieter than a naturally aspirated (N/A) car with open exhaust.

    • Formula 1 cars are naturally aspirated. The data I used for this analysis came from direct measurements done by an acoustical firm studying the Baltimore F1 track.

      Naturally aspirated or turbo, remember that these engines put over 900 HP to the transmission. That’s going to be loud no matter what kind of air handing they utilize.

  5. C'mon... Really? says:

    “It appears very likely that the track will be operating in exceedance of the Austin noise ordinance.” Umm… Forgive me but this isn’t in Austin… It’s in ELROY!!!

  6. They are loud but says:

    The study is a bit flawed. The actual cars are much louder. That being said, the cars up close are extremely loud and can be hear adistance away. From what I have seen the noise at CotA will not be as much of an impact as a direct overhead flight of a jet for the people in their homes nearby. It will be audible, but not disruptive….

    That being said, no clue what it will do to livestock.

  7. As I stated in the article, I used Indy car data, which is conservative, and it is for a single trip of a single car around the track, also very conservative. So yes, you’re right, it will be louder than my model predicts, possibly 10 dBA louder.

    At the levels predicted by the study, or louder, race car noise will be disruptive in homes located near the track. (Unless those homes have exceptional construction, which does not appear to be the case). That’s not personal opinion, that’s the appropriate conclusion to draw from the data.

    Noise from aircraft using ABIA is audbile in this area, but not comparable levels from the race cars at homes near the track. You can find a copy of the latest ABIA noise contour map in several documents online, and you can see that the 65 DNL contour is a considerable distance from the track. DNL and SPL aren’t directly comparable, DNL is a 24-hour average and SPL is a single event, but you can get a decent sense of what noise exposure from ABIA is like based on the map.

Leave a Reply

*