PennDOT is planning to replace the Commercial Street Bridge, which takes the I376 Parkway East over Commercial Street just before the Squirrel Hill Tunnel. The project is expected to go out for bid in February 2024 with the main work to be done in the summer of 2026.
As the following Noise Map1Map source here. developed by the US Department of Transportation shows, Parkway East including the Commercial Street Bridge is a major source of noise pollution.
This bridge passes over the nine-mile-run portion of Frick Park. Frick Park is one of the most utilized parks in Pittsburgh and nine-mile-run recently underwent a $7.7 million restoration.
The bridge also exposes multiple residential areas including Summerset on the Frick to noise pollution.
Unfortunately, PennDOT does not plan to incorporate sound barriers or formally study noise mitigation in the new bridge design. The reasoning PennDOT gives for this is poor. PennDOT writes:
The only time we consider a noise analysis and potential sound barrier installations is when we have a transportation project that increases the number of through lanes on the highway [or if there is a substantial change in the alignment of the highway].
This approach to noise mitigation has an anti-urban bias. Lane expansions and highway alignment changes are rare in cities because of the high cost of land and the comparatively high problems of induced traffic from highway expansions. Highway noise is a bigger problem in cities due to the high surrounding population density and more intense land use. Cities are where noise mitigation provides the largest benefits, but PennDOT’s process makes them the least likely location to be implemented!
To be fair to PennDOT, they do plan to apply a polyester polymer concrete overlay on the bridge deck, which should reduce noise levels 5-10 dB. The new bridge will also only have 2 expansion joints instead of the 5 on the existing bridge, which will reduce noise levels.
Still, more could be done to reduce noise levels. Quieter bridge joints using patterned joint cover plates would reduce noise levels 6-9 dB. Use of sound absorptive noise barriers would further reduce noise. There may be additional mitigation methods that an analysis could identify.
Noise pollution is more of a problem than most people realize.
- Chronic exposure to noise pollution increases risk of heart attacks and strokes.
- High ambient noise levels reduce people’s ability to focus. This reduces productivity for people working from home, and reduces learning and test scores in children who live near highways.
- Noise pollution also reduces property values in proximity to highways.
Even in cases like lane expansions that do qualify for a noise analysis, PennDOT only incorporates sound barriers if noise levels are expected to be above 66 dB. However, the World Health Organization has concluded that traffic noise levels above 53 dB are associated with adverse health effects. At night time, noise levels below 30 dB are needed for high quality sleep. When the population density near highways is high, PennDOT should implement more aggressive mitigations to limit noise levels to 53 dB or lower.
Better attention to highway noise pollution will make Pittsburgh and the rest of Pennsylvania a better place to live. The Commercial Street Bridge replacement is an opportunity for improvement that PennDOT should take advantage of.
