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Many residents along the Sumneytown Pike/PA 309 Connector have expressed their concern about changes in air quality and noise levels as a result of the proposed project. The following summarizes the studies conducted during the preliminary design process to fully assess and document potential noise and air impacts associated with the proposed project.
Noise Analysis
PENNDOT conducted preliminary noise studies during the environmental study phase of the project Preliminary studies include monitoring existing noise levels and modeling future noise levels. Noise monitoring has been conducted at over 25 sites during peak-traffic noise periods. In conjunction with the noise monitoring, PENNDOT takes traffic counts on all roads that influence noise levels within the Connector's study area. The traffic count data makes it possible to identify the type and amount of traffic that corresponds to the recorded noise level.
Once the noise-monitoring program was completed, noise modeling was performed to assess future (design year 2026) noise levels associated with the proposed improvement plan. These project design year noise levels were compared to PENNDOT’s Noise Abatement Criteria (NAC). In areas where noise levels exceeded the criteria, abatement was considered. According to PENNDOT and Federal Highway Administration guidelines, which must be followed for this project, noise abatement must be warranted, feasible and reasonable:
Warranted: Projected design year noise levels must be at or above 66 decibels (dBA), or must demonstrate a 10-15 dBA increase above existing noise levels to meet the warrants for noise abatement considerations. Noise levels that do not meet the criteria identified above are not considered for noise mitigation.
Feasible: This criteria includes determining whether it would be physically possible to construct noise walls or earth berms at locations under study, and whether noise abatement would provide a measurable benefit for the majority of impacted residents – noise level reduction of at least 5 dBA. Additional feasibility considerations include access and safety.
Reasonable: Cost-effectiveness of building noise walls is taken into consideration for those residences that will receive a benefit. To receive a benefit, a residence must attain a 5 dBA noise reduction. To be considered reasonable, the cost for noise abatement must not exceed $50,000 per benefited residence.
While PENNDOT evaluates the need for potential noise mitigation during preliminary design, final noise mitigation commitments will be made during the project's final design phase. The Final Design Noise Report for Phase I is complete. No noise mitigation is proposed in Phase I.
Air Quality
For this project, a quantitative air quality analysis was performed using "Inter Air", PENNDOT’s Intersection Air Quality Screening Procedure. This screening procedure provides an analysis of worst-case carbon monoxide (CO) levels, based on county-specific parameters, years of analysis, traffic volumes, traffic speeds, background CO concentrations, and intersection assumptions. As part of this analysis, PENNDOT determined that existing and future air quality conditions are within the National Ambient Air Quality Standards (NAAQS) for CO. Post construction air quality is not expected to be significantly different than existing conditions.
