The Metro D Line (Purple) Extension program, Sections 1, 2, and 3 will extend the heavy rail subway system westward from the current terminal at Wilshire Boulevard and Western Avenue. The Metro D Line Extension was designed and built in three sections. The 9-mile-long extension will include seven new stations and provide a high-capacity, high-speed, dependable alternative for those traveling to and from Los Angeles’s “second downtown,” including destinations such as Miracle Mile, Beverly Hills, Century City, and Westwood.
ENGEO provided 3rd party peer review services for the City of Beverly Hills. ENGEO also took the position of Engineer of Record on Sections 2 and 3 for the geotechnical instrumentation design and structure impact assessments which were for the support of excavation designs for the four associated stations as well as the Section 3 tail track exit shaft.
To no surprise, challenges arose from the densely populated area in which the project is located. The tunnel alignment passes through areas that have structures ranging from single-family houses to high-rise office buildings. Furthermore, structures include very sensitive historical structures; as well as, passing beneath the I-405 freeway and heavily traveled city streets, involving several third-party stakeholders.
These obstacles required accurately estimating potential ground movements and developing reasonable mitigation measures. ENGEO’s instrumentation design and structure impact assessment allows the design-build team to safely construct the stations, shafts, tunnels, and cross-passages while limiting impacts to sensitive structures and infrastructure along the alignment.