Considering the considerable impact that noise from bridge expansion joints can have on local residential communities, particularly at night, and the problems that resulting complaints may present for bridge owners, it is sometimes necessary to evaluate noise from existing expansion joints, or from proposed or already implemented solutions. A new paper entitled "Noise from bridge expansion joints – Evaluation considerations and possible reduction measures", written for this year’s New York City Bridge Conference, explores the issue of noise from bridge expansion joints, with discussion of causes/sources and possible solutions. In particular, the paper discusses principles of evaluation of noise, and of evaluation of the benefit offered by noise-reduction measures.

As concluded by the paper, noise from bridge expansion joints of certain types should be properly considered when specifying and using expansion joint solutions in bridge construction and maintenance projects. Different solutions may be appropriate, depending on the likely significance of noise emanating directly from the joint’s surface (above the level of the driving surface), or from beneath the joint (within the abutment). mageba’s solutions (as applied to the TENSA®MODULAR expansion joints of the SR520 West Approach Bridge in Washington, for instance) include the addition of noise-reducing surface plates (known as “sinus plates”) to provide the joint with a continuous driving surface, and applying the ROBO®MUTE system beneath the joint to trap and absorb noise emitting from the joint’s underside.

In evaluating the likely effectiveness of any proposed solution, a more sophisticated approach than is often taken may be possible. For instance, rather than simply evaluating the degree to which noise from a joint is reduced by a particular solution, compared to a joint that does not feature the solution, it is likely to be far more relevant to affected parties to evaluate the degree to which noise from a joint which features the solution exceeds the level of “background noise” from the road (e.g. just 1.15 dB in the presented example of truck traffic crossing a TENSA®MODULAR joint with “sinus plate” noise-reducing surfacing). Another useful approach may be to evaluate the degree to which application of the solution reduces the amount by which noise from the joint exceeds the level of “background noise” from the road (e.g. to just 22% or less for the same presented example). By sensibly determining such evaluation criteria, the effectiveness of the evaluation process during selection of an expansion joint solution for a particular structure can be considerably optimized, reducing the risk of public relations difficulties with residents in a structure’s neighborhood.