Vibration Control Design for Light Rail Transit: A Single Project With the Full Rainbow of Vibration Control Features: Case Study

Because of the recent emphasis on rail transit infrastructure expansion and rebuilding in the United States, there is concern about the potential adverse vibration effects on existing activities that are sensitive to vibration and ground-borne-noise located in proximity to new or reactivated rail system rights-of-way. A Southern California at-grade/elevated LRT system that is currently under construction required the design and specification of extensive vibration control features. The final design needed to include the entire range of vibration mitigation tools presented in the Federal Transit Administration guidance manual. Designs and Contract Specifications included simple single-layer ballast mats; multi-layer ballast mats; high-resilience direct fixation fasteners; potential wheel-squeal solutions; low-vibration special trackwork; continuously-supported, street-running, floating slab track; and discrete, steel-helical-spring-supported floating slab track. It is noteworthy that the discrete steel-spring-supported FST is the first use of this vibration control approach in an at-grade rail system in the United States. This paper will discuss the overall approach, data analysis, solutions development, and the final designs prepared for this project and how this information may be beneficial to other projects with similar issues.