Metro Gold Line Light Rail Transit System
Los Angeles to Pasadena, California
Los Angeles Metro Gold Line Construction Authority
Since 1999, ATS has provided acoustical consulting services to the Metro Gold Line Construction Authority (formerly Blue Line Construction Authority) on technical, regulatory, legal, and political issues associated with noise and vibration for a new 14-mile LRT system connecting downtown Los Angeles with Pasadena.
During this time, our role has included completing a system-wide noise and vibration assessment in support of the environmental review, performing site specific noise and vibration testing as part of project engineering, helping procure special direct-fixation fasteners for construction, and a variety of key strategic services associated with legal and regulatory challenges. In addition, ATS participated in or directed one-on-one and group meetings with citizens, business owners, and politicians.
ATS has been responsible for resolving noise issues for a variety of sensitive receptors throughout the three communities served by the project. One particular concern was the effect of light-rail operations on a historic movie studio. ATS directed sound insulation tests at the studio to identify the transmission loss characteristics of specific production areas. Extensive mitigation, including a 25-foot high sound wall and building improvements, was implemented to ensure that train noise does not disrupt filming and audio recording. ATS also prepared technical analyses for all commercial and residential uses along the alignment. A key part of many of these analyses was our one-on-one involvement with concerned community members and organizations in explaining noise concepts, presenting study results, and discussing mitigation options.
ATS assisted in the transition from final engineering to the design/build contract and project construction. In particular, the ATS team has been responsible for gathering and synthesizing project information and technical data that provided the basis for a new environmental document and further engineering. The review also required system-wide noise and vibration analysis based on current design and operational parameters.
As part of project construction, ATS directed a series of vibration propagation tests for the cut-and-cover tunnel through “Old-Town” Pasadena. This tunnel structure was constructed adjacent to commercial and residential buildings, some being historic. State-of-the-art testing of the local vibration propagation characteristics, combined with previous testing of the selected light-rail vehicle, also directed by ATS, was used to predict ground-borne noise and vibration levels inside structures adjacent to the tunnel. Based on the results, ATS prepared a technical specification that generated a competitive bid for special vibration-reducing direct-fixation track fasteners.
ATS also assisted the Authority’s executive management and legal counsel design and implement a defense for claims regarding noise and vibration. An action filed with the California Public Utilities Commission (CPUC) led to a multi-party settlement. As part of this process, ATS provided expert services and acted as a liaison between the transit authorities, regulatory agencies, and outside stakeholders involved in the dispute. In large part, the success of this process was due to our ability to reasonably interpret and apply standards, to understand the concerns and objectives of all parties, to clearly communicate technical concepts, and to engineer a consensus on the critical issues.
The specific commitments in the settlement came from a comprehensive review of operational noise levels completed by ATS. As traditional mitigation measures, such as sound walls and residential sound insulation, had already been installed and many of the complaints were based on annoyance and not the absolute sound level, ATS investigated non-standard means to improve local conditions. Our recommendations, which included minimizing wheel squeal and modifying the grade-crossing audible-warning devices, were not only cost-effective but also addressed the root causes of the complaints.
ATS is currently working on the Foothill Extension to the Gold Line: the Construction Management Team for the Phase 2A extension to Azusa and the Supplementary EIS/R for the extension from Azusa to Montclair.