Road Traffic Noise

Overview

Engineering reference data for Road Traffic Noise in acoustics.

Key Formulas

Speed of Sound

$c = \sqrt{\gamma R T}$

Speed of sound in an ideal gas.

Sound Level

$L = 10 \log_{10}(I/I_0)$

Decibel level.

Wavelength

$\lambda = c / f$

Wavelength = speed / frequency.

Variables

Practical Example

A quick calculation based on typical charts for road traffic noise:

• Given: A road with 100 vehicles per hour at a speed of 75 km/h.
• *Step 1: From the standard noise level chart, the base hourly noise level is approximately 62 dBA.
• *Step 2: The percentage of heavy vehicles is 15%. A correction chart indicates an addition of 3 dBA.
• Result: The estimated hourly noise level is $62 \text{ dBA} + 3 \text{ dBA} = 65 \text{ dBA}$.

Note: This is an indicative value. Actual noise levels are subject to many variables.

Factors Influencing Noise Levels

The calculated noise level is only an approximation. The actual sound pressure level from road traffic is significantly influenced by:

• Vehicle speed
• Vehicle standard and type (e.g., cars vs. trucks)
• Road surface quality (tarmac condition)
• Tire type and condition (e.g., with or without studs)
• Traffic flow dynamics (acceleration, braking)
• Environmental conditions (e.g., temperature, wind)

References

• Original Source