TYLin provided preliminary engineering and final design of the Division 20 Portal Widening and Turnback Facility in Los Angeles, California.
The Division 20 Portal Widening and Turnback Facility project will enhance the Los Angeles County Metropolitan Transportation Authority's (L.A. Metro) Purple and Red Line service operations to 90-second headways. A required component of the Westside Purple Line Extension Project, this project widens the existing tunnel portal and reconfigures the tracks, improving safety and operational reliability and allowing for increased train speeds. TYLin is providing bid support and design services during construction, which is slated for completion in summer 2024.
Working closely with L.A. Metro's Operations and Planning staff, TYLin developed and evaluated alternatives for the existing complex turnback facility. The selected option maximizes operational efficiency and provides for a future extension to the Arts District. In addition, trackwork extending south from Union Station to the Arts District has been designed to support a future station at Sixth Street.
TYLin designed two additional train storage yards north and south of the existing First Street Bridge and was responsible for train control, communications, and electrical upgrades. We also strengthened and modified the historic bridge to eliminate conflicting piers while preserving its character.
TYLin collaborated with L.A. Metro to reconfigure the preliminary turnback facility design and eliminate encroachment into a BNSF Railway property. This improved construction feasibility and helped L.A. Metro save land acquisition costs. By developing multiple trackwork alternatives, we also identified a configuration that provides superior operational functionality while preserving the option of extending revenue service to Sixth Street.
The complete reconstruction of the existing tunnel portal and trench section was designed as part of the project. We also coordinated with California High-Speed Rail Authority (CHSR) to ensure that a future viaduct straddling the portal will be feasible.
TYLin project innovations include:
- Since the alignment of the Link US project interfaces with the Division 20 yard at the portal location, we provided structural and cost analysis to avoid redundant modifications and reduce impacts on operations during future construction phases.
- We designed a cap to the portal structure to allow for Link US loads, ultimately resulting in significant cost savings to L.A. Metro.
- To optimize construction staging and gain time in the construction schedule, TYLin repackaged the project to address long-lead items while maintaining the final construction completion date. The resulting four packages focused on the early demolition of existing structures, advance procurement for a traction power substation, early construction of duct banks, and the main project construction.
- The project was completed in an active freight/commuter corridor and included a new transit station and accommodations for future CHSR tracks.
- TYLin provided fast-track design, utilized the latest L.A. Metro design standards, and coordinated with L.A. Metro, the California Department of Transportation, and the California Public Utilities Commission.
- Due to many other concurrent construction projects in the vicinity, TYLin worked closely with L.A. Metro to incorporate the needs of the other projects into our design.
- The design team worked closely with the City of Los Angeles Fire Department and L.A. Metro's Fire Life Safety Department to provide added safety features to the existing and new yard to support the project improvements and prepare for potential future revenue service through the yard to a Sixth Street Station.
- Among the many safety features, the project team designed raised emergency walkways through the open stretch of the yard. This decision sets precedence for at-grade heavy rail along L.A. Metro's system.