The project noise assessment is being performed in accordance with Federal Highway and PennDOT guidelines. Which are outlined in PennDOT’s publication 24, which is a publicly available document online. The design year build conditions around levels determine impacts and vary by land use, so for example residential impacts thresholds typically occur around 66 decibels.
Impacted land use warrant abatement consideration, typically provided in the form of sound walls. Warranted abatement options are then assessed for feasibility, which is constructability and reasonableness which evaluates cost effectiveness and the performance of any proposed barriers or noise barriers in that case.