Over a three year period Wakefield Acoustics Ltd. carried out community noise studies related to a new crossing of the Fraser River located east of Vancouver and connecting Surrey and Langley on the south side to Pitt Meadows and Maple Ridge on the north side. Originally referred to as the New Fraser River Crossing, the structure was later renamed the Golden Ears Bridge to reflect the mountain views which the bridge afforded of a nearby regional park of that name. Wakefield Acoustics Ltd.’s first assignment involved assessing the potential noise impacts of several possible alignments options for the bridge and its connecting highways, while the second was the a community noise impact assessment as part of the project’s Environmental Impact Assessment.
Wakefield Acoustics Ltd. were retained by the facility’s owner, TransLink, to provide owner’s review services regarding noise issues. In this capacity, Wakefield Acoustics Ltd. was asked to investigate the unexpected noise created by the bridge’s many modular expansion joints. A unique “croaking” sound occurred when tires rolled over the many parallel “lamella beams” that formed the upper surface of each expansion joint. This noise resulted in immediate negative community reaction when the bridge opened. Over the next two years, Wakefield Acoustics Ltd. worked with TransLink to document to the nature of this noise, identify the acoustic source mechanism behind it, and develop and test various mitigation measures. An effective solution was reached with the insertion of an optimized sound absorptive material into the cavities between the lamella beams of each joint. These inserts were secured with solid rubber caps bonded to the lamella beams and were found to reduce croaking noise levels at the residences by approximately 10 dBA.