How loud is highway traffic?
Highway traffic is about 76 to 80 dBA at 50 feet (15 m) from the road. A Purdue University chart lists a freeway at 76 dB from the pavement edge at 10 a.m., and Environmental Health Perspectives says a busy freeway at 50 feet is around 80 dBA. The same Purdue chart gives 77 dB for a single car at 65 mph and 25 feet.
- Level
- 76–80 dBAA-weighted sound level
- Distance
- 15 m50 ft (15 m) from the road
- Daily limit
- No daily limitNIOSH, at the loud end
- Versus conversation
- 35× energyabout 2.9× as loud
What the numbers mean
How it was measured. A busy freeway heard from 50 feet. Purdue University's chart gives 76 dB at 50 ft from the pavement edge at 10 a.m. (weighting not stated); Environmental Health Perspectives puts a busy freeway at 50 feet at around 80 dBA. Traffic volume, speed and road surface are not given.
Both figures are for the roadside at 50 feet, about the distance from the nearest lane to the first row of houses on many roads. Purdue's chart, compiled from Temple University and the US Federal Interagency Committee on Noise, gives 76 dB at a stated time of day, 10 a.m.; Environmental Health Perspectives gives around 80 dBA for a busy freeway. Heavier traffic, more lorries and higher speeds push the level up.
A busy road behaves less like one noisy car than like a line of them. The Federal Highway Administration's noise glossary describes a continuous stream of traffic as a line source whose sound spreads cylindrically, while a single vehicle pass-by spreads spherically from a point. The practical result is that a busy highway fades more slowly as you walk away from it than a single passing car does.
How long is safe?
Below 85 dBA, the level NIOSH allows for a full 8-hour day.
| Level | NIOSH limit (85 dBA, 3 dB rule) | OSHA limit (90 dBA, 5 dB rule) | UK/EU 80 dB(A) action value reached after | UK/EU 85 dB(A) action value reached after |
|---|---|---|---|---|
| 76 dBA | No limit | No limit | Not reached in 24 h | Not reached in 24 h |
| 80 dBA | No limit | No limit | Not reached in 24 h | Not reached in 24 h |
Times are for a whole day’s exposure, with the rest of the day quiet. The workplace limits were written for adults at work, not for children. Work out a mixed day with the noise dose calculator.
Protecting your hearing
A few minutes beside a highway is not a hearing risk, but road crews and others who spend whole shifts at the roadside get closer to the 85 dBA, 8-hour NIOSH limit, especially nearer the lanes. At home, bedrooms facing away from the road help sleep.
Earplug and earmuff ratings (NRR in the US, SNR in the UK and EU) are lab figures; real-world protection is usually lower. How to read the ratings.
Compared with sounds nearby
Using midpoints of each range. Energy multiplies by 10 every 10 dB; perceived loudness roughly doubles (why).
- Busy restaurant (65–85 dBA): this has about 2× its sound energy and sounds about 1.2× as loud.
- City bus (75.3–76 dBA): this has about 1.7× its sound energy and sounds about 1.2× as loud.
- Electric lawn mower (82 dBA): it has about 2.5× the sound energy of this and sounds about 1.3× as loud.
- Street sweeper (82 dBA max): it has about 2.5× the sound energy of this and sounds about 1.3× as loud.
- Normal conversation (55–70 dBA): this has about 35× its energy and sounds about 2.9× as loud.
Questions
How many decibels is a highway?
About 76 to 80 dBA at 50 feet (15 m): 76 dB on Purdue University's chart, from the pavement edge at 10 a.m., and around 80 dBA for a busy freeway in Environmental Health Perspectives.
How loud is one car passing on the highway?
Purdue's chart gives 77 dB for a passenger car at 65 mph, 25 feet away.
Sources
- Noise Comparisons (Noise Sources and Their Effects), Purdue University Department of Chemistry, Chemical Safety. Supports: dB_low: 76 dB at 50 ft (weighting not stated).
freeway at 50 ft from pavement edge 10 a.m. (76 dB)
Checked 2026-11-04. - Decibel Hell: The Effects of Living in a Noisy World, Environmental Health Perspectives (NIEHS). Supports: dB_high: about 80 dBA at 50 ft.
a busy freeway at 50 feet is around 80 dBA
Checked 2026-11-04. - Noise Comparisons (Noise Sources and Their Effects), Purdue University Department of Chemistry, Chemical Safety. Supports: single car comparison: 77 dB at 25 ft.
Passenger car at 65 mph at 25 ft (77 dB)
Checked 2026-11-04. - Noise Comparisons (Noise Sources and Their Effects), Purdue University Department of Chemistry, Chemical Safety. Supports: chart's compiled sources.
Temple University Department of Civil/Environmental Engineering
Checked 2026-11-04. - 2.0 Terminology - Construction Noise Handbook, Federal Highway Administration (US DOT). Supports: traffic as a line source.
Cylindrical divergence is that which would occur for sound emanating from a line source
Checked 2026-11-04.
This page is general information, not medical advice. If you have ringing in your ears, muffled hearing or any change in your hearing, see an audiologist or your doctor.