Given the length of the corridor, number of residential areas and limited number of hours in the morning and afternoon for measurements, ADOT anticipates that each round of noise measurements will take approximately three to four weeks to complete. ADOT will make every effort to complete the measurements as quickly as possible, but also must account for unforeseen events that might require repeating of noise measurements.
At this time, ADOT is not scheduling noise measurements at specific homes or locations upon request. In alignment with the Final EIS, ADOT will conduct noise measurements in noise-sensitive areas along the entire corridor and share the results of decibel readings in correlation with each location.
While there are many factors that may have a potential to influence traffic noise, traffic volume is the predominant factor. With that said, traffic is at its loudest when the traffic operates at Level of Service C. This is the condition of a stable flow of vehicles, at or near free flow in a lane, but lane changing and maneuverability may be challenging. During Level of Service C at 70 mph, there are approximately 1,500 vehicles per hour and per lane. When traffic volumes increase beyond Level of Service C, vehicle speeds decrease and lower the noise levels.
ADOT utilizes data collected from the permanent automatic traffic recorders, an integral part of ADOT’s traffic data management system. That data will provide hourly/daily traffic patterns which, in turn, will provide the periods that the freeway operates at or close to “level of service c” – the highest level of traffic noise based on traffic volume and travel speeds. ADOT will continue to evaluate data and determine 2.5-hour windows of time - in the morning and afternoon - with similar traffic volumes when testing would occur.
Measurements will be taken at representative locations along the South Mountain Freeway; that is, residential neighborhoods, parks, schools and similar locations. Measurements are typically restricted to exterior areas of frequent human use. Interior measurements are taken only when there are no outside activities, such as at churches, hospitals and libraries.
Because of the COVID-19 pandemic, average daily traffic volumes throughout Maricopa county are lower than usual. Taking noise measurements during this pandemic is not representative of typical traffic noise levels. ADOT is planning to resume field noise testing in late summer/early fall 2020 and in late February/early March 2021. Beyond that, ADOT will continue testing noise levels throughout the 22-mile corridor regularly in select locations. Schedules are subject to change because of the pandemic and other unforeseen situations.
“Fully operational” means that the monitoring systems and overall conditions on the freeway are conducive to continuous, uninterrupted, and free-flow traffic operations, and that the traffic volumes are aligned with the levels predicted by the Maricopa Association of Governments (MAG) travel demand model for the year 2020.
ADOT is conducting noise measurements in compliance with the Final Environmental Impact Statement (FEIS) for the South Mountain Freeway. Further, ADOT will evaluate the common noise environment within the project area after the freeway is “fully operational.”
An email from the IISP to notify us and then update it on the monthly report marking changes the first month in Red. After the first month, the report can reflect black font color again.