“Trees and natural things that absorb sound is a really good way to help treat noise”
By Tim De Petris and Tazwar Shahnawaz
A mess of red construction cranes seize the blue sky like gnarled fingers pointing every which way, a sign of progress for a highway cap project underway in Philadelphia that aims to reconnect Old City to the Delaware River.
The planned structure over I-95, as well as another over I-676, may provide another, more tangible benefit: noise reduction.
The Park at Penn’s Landing, an 11.5 acre park between Chestnut and Walnut streets, and the Chinatown Stitch, a set of two caps which will join the divided sections of the neighborhood, could dampen noise from the highways in their respective areas, improving quality of life and health for nearby residents.
A highway cap is a structure built over a roadway typically featuring green space or new buildings. Caps restore connections between parts of city’s previously divided by highways, allowing people to cross by foot.
Though the projects’ explicit goals are to undo the historic harms of both highways’ constructions, they are progressing as a growing amount of research shows chronic noise is bad for heart health.
“Noise is a kind of psychosocial stressor,” said Omar Hahad, a cardiology researcher at the Johannes Gutenberg University in Mainz, Germany. “It can induce stress reactions, increase blood pressure and heart rate in the short term.”
Increased noise pollution from cars was associated with a greater chance of dying from cardiovascular diseases in a Swiss study of 4 million adults published in 2022. Noise pollution can also interfere with sleep cycles and has been directly linked to mental illnesses like depression, anxiety and dementia, Hahad said.
Chronic noise can activate the brain’s stress response, said Michelle Temple, a professor of music technology and researcher in sonic warfare at Temple University.
“There’s some portion of your brain that is always processing that you are in a fight or flight situation,” Temple said.
Around the project sites in Philadelphia, decibel readings recorded on a smartphone in the early afternoon registered between 70 and 85, comparable to a lawnmower.
Hahad estimated the city’s projects could reduce noise anywhere from two to ten decibels depending on the construction materials, whether they fully cover the roadway, and if there are gaps for ventilation.
Construction is underway at the Park at Penn’s Landing and is expected to finish by Spring 2028. The Chinatown Stitch is still in planning and will not start construction until at least 2028.
While the Park at Penn’s Landing will reduce noise pollution in the area, “noise mitigation was not a direct intention of the design of the new park,” according to a statement by the Delaware River Waterfront Corporation, the group behind the park project.
Philadelphia is far from the first city to build highway caps. Nearly two decades ago, Boston’s “Big Dig” project, which rerouted I-93 from an elevated highway to a tunnel, was credited with reducing noise in surrounding neighborhoods between 25 and 33 percent.
The Biden Administration granted $544 million to cities via a program aimed at reconnecting communities divided by transportation infrastructure in 2024.
Among the awardees were highway cap projects in Chicago and Baltimore, as well as the Chinatown Stitch. Each project aims to include parks and green spaces.
“Trees and natural things that absorb sound is a really good way to help treat noise so it’s not as intense,” Temple said.
The Park at Penn’s Landing will include ice skating rinks, walkways, open green space and a large pavilion for gatherings.
Philadelphia’s Office of Transportation and Infrastructure Systems was unavailable for comment on the Chinatown Stitch.