Soundscape / Noise

Natural soundscapes exist in the absence of human-caused sound, and the natural ambient soundscape is the aggregate of all the natural sounds that occur in park units, together with the physical capacity for transmitting natural sounds. At Valley Forge NHP, no area of the park is farther than 2,000 feet from a road or railroad. Because the park is surrounded by development and riddled with through-traffic, natural soundscapes do not exist within the park. An examination of existing sound levels is important, however, to assess the impacts of proposed traffic improvements and the placement of vegetated buffers to minimize excessive noise levels.

Noise measurements related to traffic studies were conducted at Valley Forge NHP in August 2001 and March 2003. Equivalent noise levels (Leq) represent average sound levels from a sound energy standpoint expressed in decibels on the A-weighted scale (dBA). Highly significant highway noise was noted in several locations along exterior and interior portions of the park. Within 300 feet of PA Route 23, noise levels remained relatively constant ranging from 49 dBA at night to 58 dBA during rush hour. These sounds are comparable to the indoor sound of a dishwasher in the next room. Another sampling point was taken between PA Route 23 and the Norfolk & Southern Railroad corridor. This point experienced a noticeably wider range of sound levels, 46-75 dBA. This higher range is attributed to rail noise. The relatively quiet Schuylkill River corridor was regularly affected by rail noise. The louder noises are comparable to someone shouting within one meter of the listener.

High noise levels were also identified close to Pawlings Road. Within 100 feet of the road, sounds ranged from 58-65 dBA. These levels were slightly exceeded at the western approach to the park (67 dBA).

Measurements taken along Outer Line Drive ranged from 49 to 55 dBA during peak hours. Although Outer Line Drive has relatively low traffic levels, field observations indicate that the noise impacts are a combination of local sounds with noise from other sources, such as the PA Turnpike. The southern portion of the park was identified as having a much narrower range of noise levels, from 53 to 54 dBA, attributed to the closeness of the turnpike. Turnpike noise at Lafayette’s Quarters is particularly intrusive.