Highway traffic as a noise source creates complexities when it comes to analysis and mitigation, and ADOT understands that you may have additional questions. There are many factors, all of which are relevant, such as traffic volumes and speed, traffic mix, pavement and atmospheric conditions that can impact noise levels. That is why the Federal Highway Administration has provided regulation and guidance on how to analyze and mitigate highway-related noise. The following resources provide information you might find useful:
FHWA - Highway Traffic and Construction Noise - Regulation and Guidance:
https://www.fhwa.dot.gov/Environment/noise/regulations_ and_guidance/
FHWA - Noise Policy FAQs - Frequently Asked Questions:
https://www.fhwa.dot.gov/environment/noise/regulations_ and_guidance/faq_nois.cfm
ADOT – Environmental Planning – Noise:
/business/environmental-planning/noise
US DOT - National Transportation Library: