Expansion joints are connections in bridges that allow the structure to expand and contract with changing conditions such as temperature, lake level, wind/wave conditions, and traffic loads. These expansions and contractions prevent the bridge from becoming overstressed and being damaged. Modular expansion joints are typically used when six inches or more of expansion/contraction are required at a joint. More than 50 WSDOT bridges statewide have modular expansion joints, including the Evergreen Point Floating Bridge (SR 520), which has sixteen center beam expansion joints on the east and west ends. The noise created when vehicles drive over modular expansion joints is a nuisance to nearby residents, and WSDOT receives numerous noise complaints associated with modular bridge expansion joints throughout the state. This study aims to develop a noise mitigation method that reduces environmental noise levels. Phase 1 of this study examined the noise generation mechanism and its radiation from expansion joints. This phase 2 study will develop ways to mitigate the noise, as no commercially available noise abatement exists that is cost effective, safe, and durable. The project will include both laboratory and field studies of potential sound mitigation systems to determine their effectiveness, viability, durability, and safety. The results will be applicable to all existing and future bridges with these types of expansion joints and will help improve the quality of life for residents living near these bridges.
Principal Investigators:
Per Reinhall, Mechanical Engineering, UW
Jeff Lipton, Mechanical Engineering, UW
Sponsor: WSDOT
WSDOT Technical Monitor: Mark Gaines
WSDOT Project Manager: Jon Peterson
Scheduled completion: December 2022