Crossing the Fraser River in the shadows of its namesake mountains, the Golden Ears Bridge spans 976 metres. This makes it North America's longest extradosed bridge, a form that blends the design elements of box girder and cable-stayed bridges. BKL joined the Public Private Partnership (P3) Golden Ears Bridge Project joint venture team in 2005 as the project acoustical consultant until its completion in 2009. In addition to the bridge, which is owned by TransLink, the project included 1.4 kilometres of approaches and Golden Ears Way, 12 kilometres of new road from Highway 15, Surrey, to 203rd Street, Maple Ridge. BKL's first task was to develop a construction noise management and monitoring plan for the project. This site-specific plan was created to limit the effects of construction noise on nearby residences and ensure that noise levels would meet the criteria of municipal bylaws, worker safety regulations, and the project's agreement with the nearby Katzie First Nation (KFN). The plan included best management practices to minimize construction noise at the sources and avoid noise impacts when conducting construction activities. The project agreement required mitigating future traffic noise in accordance with the Ministry of Transportation and Infrastructure's highway noise policy. BKL assessed potential road traffic noise in residential neighbourhoods in KFN, Pitt Meadows, Maple Ridge, Langley, and Surrey, at more than 150 residences. BKL met with concerned residents to understand their noise concerns, such as rail noise reflections off the underside of the rail overpass deck, the bus-only on-ramp from Hammond Road, and the behaviour of low-noise pavement in wet conditions, and ensured that these factors would be taken into account in addition to the other requirements of the ministry's policy. Predictions for operations noise—that is, road traffic on the bridge, its approaches, and the connected roadways—revealed that levels would exceed the project criteria at some residential areas. Of these locations, BKL highlighted which would qualify for noise mitigation, based on the ministry's policy, and outlined various mitigation options. Finally, BKL supported the design team in developing a noise barrier specification, performing noise modelling of the detailed design's noise barrier alignments, and reviewing noise wall shop drawings. BKL met with Katzie First Nation and developed a separate plan for monitoring, assessing, and mitigating construction and operations noise on its lands. BKL performed a detailed noise assessment of the contractor's proposed construction activities on KFN lands using 3-D outdoor sound propagation software Cadna/A, including how noise might affect cultural land uses, for example, at the longhouses. BKL then performed noise monitoring at key KFN locations throughout the duration of the project. In July 2009, with the bridge open to traffic, BKL conducted post-construction noise barrier insertion loss measurements, in accordance with American National Standards Institute (ANSI) standard S12.8, to ensure the mitigation was effective. Also, to confirm predictions completed during the Environmental Assessment Certificate (EAC) application, BKL monitored operational noise at 12 locations identified in the EAC as potentially requiring mitigation. BKL joined the Golden Ears Bridge project joint venture team early, and committed experienced consultants and equipment resources for the duration. For over four years, from bid phase to post-construction monitoring, BKL's acoustical engineers worked closely with the client and members of public where required, including the Katzie First Nation, to monitor and assess noise; recommend solutions where needed; and, through accurate, detailed reporting, communicate the effectiveness of the solutions. Have a project in mind? Get in touch today.