City Hall Station is the busiest station on the Broad Street Subway Line in Philadelphia, serving over 57,000 passengers daily. With so much foot traffic, Southeastern Pennsylvania Transit Authority’s (SEPTA) decided to solve the serious acoustical deficiencies of the station.
Cerami conducted an extensive noise and vibration study on the train platforms, the station proper, and the non-SEPTA properties adjacent to the station, and found noise levels were often twice as loud as SEPTA’s design criteria and acoustical standards. One problem, reverberation, was addressed by an optimized distribution of suitable sound absorptive materials that could withstand the station’s rough environment. The mitigation of structureborne noise generated at the tracks and transmitted to adjacent structures was solved with the cost-effective and minimially-disruptive solution of using a continuous, welded rail system. By smoothing out the tracks, the screeching noise from the wheel/track interaction on inconsistent surfaces was significantly reduced.
Or AV team’s study concluded that sound coverage, articulation loss of consonants percentage, and signal-to-noise ratio were the major problems for patrons, so suitable equipment and proper placement of loudspeakers and paging systems were identified. Cerami also recommended new control systems that expand master and station control capabilities, monitors that register and announce the status of arriving trains, and the ability to edit and transmit announcements in digitized audio to local stations and to remote sites. Centrally-controlled monitor screens were placed throughout provide the passengers with timely visual announcements.