Day/Night Noise Level Electronic Assessment Tool
The Environmental Planning Division has developed an electronic assessment tool that calculates the Day/Night Noise Level (DNL) from roadway and railway traffic. This is a web-based application of the existing Noise Assessment Guidelines (NAG). It is a component of the Assessment Tools for Environmental Compliance (ATEC). Derivations of the basic noise equation from the noise regulation, 24 CFR Part 51 Subpart B, were applied to a new application of the NAG.
Noise from aircraft and loud impulse sounds are addressed through this tool as well. Aircraft noise data, available from the neighboring airports, may be input for inclusion in the total site exposure. Loud impulse sounds are similarly accommodated once their presence has been confirmed.
Site Acceptability Standards:
- Exterior noise levels – Proposed HUD-assisted projects with a day-night average sound level of below 65 decibels are acceptable (see Standards in 24 CFR Part 51.103).
- Interior noise levels – Proposed HUD-assisted projects with a day-night average sound level of below 45 decibels are acceptable.
Additional guidance on how to calculate the DNL for a proposed HUD-assisted project is available in the Department's guidebook “The Noise Guidebook" and the regulation 24 CFR Part 51 Subpart B, Noise Abatement and Control.
To use the DNL calculator, click on the following link: DNL Calculator