This map shows modeled outdoor noise across 94947 at 100-meter resolution, combining road, aviation, and rail sources. Green areas measure below 45 dBA. Orange and red exceed the EPA's 55 dBA outdoor threshold linked to long-term health effects. Use the layer toggles to view each source on its own or all together.
What the numbers sound like
- 30 dBAWhisper
- 40 dBASoft rainfall
- 45 dBAQuiet suburban street at night
- 50 dBAQuiet office
- 55 dBAEPA outdoor threshold: light traffic 100 ft away
- 60 dBANormal conversation an arm's length away
- 65 dBABusy restaurant
- 70 dBAHighway traffic 50 ft away
- 80 dBACity bus interior
Population Above the EPA Outdoor Threshold
The EPA's 55 dBA outdoor reference level is a common benchmark for residential noise exposure, especially for activity interference, annoyance, and long-term community noise concerns. About 5,636 94947 residents, or 23.4%, live above that level. By land area, 27.1% of 94947 is above 55 dBA.
See how noise in 94947 compares to similar-sized zip codes.
Noise by Part of 94947
Average noise levels for 94947 residents, grouped by direction from the center of 94947. The highest population-weighted average is in eastern 94947; the lowest is in western 94947, where just 3% of residents live in blocks above the EPA's 55 dBA threshold, a fifth of the share in the loudest section.
Eastern 94947
35% of people above 55 dBA
Southeastern 94947
34% of people above 55 dBA
Northwestern 94947
13% of people above 55 dBA
Southwestern 94947
4% of people above 55 dBA
Western 94947
3% of people above 55 dBA
To the human ear, noise in eastern 94947 sounds about 135% louder than in western 94947, a 12.3 dBA gap. Every 10 dBA roughly doubles perceived loudness. Within any of these directions, two homes a quarter mile apart can still differ by 10 or more dBA depending on how close they sit to a major highway.
How far back from Redwood Hwy do you need to be?
Redwood Hwy produces an estimated 78 dBA at its loudest centerline points. Noise drops logarithmically with distance, with the exact rate depending on what's between you and the road. Tree cover, walls, terrain, and pavement type all matter. At roughly a quarter mile back, traffic fades into the noise level of a quiet suburban street at night.
Calculated from the model's calibrated attenuation formula. About 18% of 94947 sits under tree canopy (about average for zip codes) and roughly 30% is impervious surface like pavement and rooftops. Both are folded into the per-place decay rate above. Heavier canopy pulls noise down faster with distance; impervious surfaces slow the drop.