Studying Sound

Written by Scott Kratz

The 11th Street Bridge Park’s mission to bring a unique community-driven facility to D.C.  residents on both sides of the Anacostia River and the larger region very much resonates with Cerami. The diverse park programs and activities requested by the community will include group activities, performance venues and  active and quiet areas, some of which may require a specific acoustical environment to perform at their best.

With the launch of a nationwide design competition, it became clear to the design teams and park staff that noise conditions at the site needed to be understood to provide a basis for the optimal design of the Park as architect and landscape architects areas balance more active areas with passive and quiet locations. Cerami made a commitment to be part of the team to advance the goals of the 11th Street Bridge Park by providing an acoustical review and guidance to the design teams.

The first step in the project was  to understand the existing conditions. Cerami’s team, Andy Parise, Geoffrey Sparks and Chris Pollock made a number of measurements at the site at a variety of locations, (made a little more difficult by not have an actual bridge park installed yet) to represent the noise levels at various times of day and locations. Most often, site noise measurements can be enlightening on a technical level, but in the case of our time spent at the 11th Street Bridge Park the beauty of the Park confirmed the need to create a  successful park for the educational, arts and community programs planned for the proposed space.

Photograph 1: The Future 11th Street Bridge Park, from Anacostia Park looking Northwest.
The noise measurements taken on weekdays and weekends, morning and evenings enabled an assessment of the space and all of the noise sources in play, including traffic on the local street and highways and the more rare aircraft and helicopters, both commercial and military.

The noise assessment also provide guidance on the optimal locations for each program type, as well as possible mitigation and construction options, including elevations and barriers, construction of  classrooms to limit noise intrusion and the use of water features to generate a natural background sound to mask traffic noise from nearby roads.

One of the key findings of the study was that the quietest locations were the two river bank locations on each side of the Park. These two spaces are lower than the roadway elevations and partially shielded from the traffic noise and nearby highways and represent the ideal locations for programs requiring a lower noise condition for their successful operation. The other key input from the noise study was the need for mitigation at a future performance venue, another community requested programming concept. An amphitheater for music, lectures or drama works best if the audience is provided with an environment where sound from the stage is readily audible and clearly above the ambient noise conditions. To achieve this with a venue located near the roadways and associated noise will require some mitigation in the form of barriers, walls or berms to limit the existing traffic noise and ensure  future audiences can enjoy the space.

The talented designers in the competition and the supporters of the 11th Street Bridge Park will soon bring the Park closer to reality which will serve as an amazing community resource. Cerami looks forward to continuing to help realize this vision.

Photograph 2: The Future 11th Street Bridge Park at Sunset, from the existing bridge Piers.