C+S January 2023 Vol. 9 Issue 1 (web)

Section 3 – Westwood/ VA Hospital Station Tunneling Site

The maintenance of way (MOW) building constructed as part of the project is located on a brownfield site that was successfully remediated by removing underground storage tanks and contaminated soil. Addi - tionally, the project team actively treated an underground hydrocarbon plume left by the former industrial facility. “We engaged a third-party commissioning agent to oversee the inte - gration of the various mechanical, electrical and plumbing systems to maximize the efficiency and performance of the MOW building man - agement system,” Kothari said. “The building features a 353-kilowatt photovoltaic system over rooftop parking, which was a major contribu- tor to achieving a LEED Gold certification from the U.S. Green Build - ing Council.” The project team also incorporated a value engineering proposal (VEP) proposed by the Section 2 Design/Build Contractor, Tutor Perini/O&G JV into the tunnel segments, which allowed the use of a specially re - inforced concrete segmental lining in lieu of a steel segmental lining through an area of seismic faults. The special concrete lining consists of hoop reinforcement with con- tinuous bars, dense rebar mats, additional steel fibers and the installa - tion of interior bands to mitigate soil and water ingress in the event of a seismic event. The VEP was a collaborative effort between Metro, The use of building information modeling (BIM) has added value to the project through near-real-time collaboration amongst all the many disciplines of the design teams and with the client which accelerated the design development process. “Modular stations were envisioned to improve system-wide unifor - mity, and BIM facilitated the highly-coordinated development of these modules which were then strategically combined based on site-specific constraints,” Kothari said. “BIM was used to model existing condi - tions, such as building foundations and utilities, which led to a much more advanced preliminary design since conflicts with the proposed design were identified and resolved early.” WSP and the contractor. Communication Tools

Section 2 - Wilshire/Rodeo Station

ing the early stages of a fire. Downstand enclosures around the vertical circulation (stairway and escalator) openings are designed to prevent smoke from rising into the concourse, allowing those areas to remain free of smoke and allow patrons to move to a point of safety. A large over-platform exhaust (OPE) duct/plenum will be placed over the platform with chimneys alongside the concourse. This design was verified using computational fluid dynamics (CFD) to analyze the con - vey smoke from an under-concourse train fire into the OPE. To address Metro’s concerns for protecting patrons during a fire in the crossover, during the final stages of design an internal exhaust plenum connecting the tunnel end of the crossover to the emergency ventilation fan plenum was added. “This will allow for smoke extraction at either end of the crossover, permitting evacuation in either direction after identification of the loca - tion of the railcar fire,” Kothari said. Other technology incorporated during the Advance Preliminary En - gineering phase was the use of platform heat detectors to quickly activate the emergency ventilation system and the use of Revit 3D design software to model the station, which in turn was used to pre- pare the CFD model. “Many of these innovative ideas came as a need to solve unique prob - lems created by the large fire and were initiated by WSP’s ventilation ex - pert William Kennedy, who passed away in 2012,” Kothari said. “It was designed in conjunction with the Purple Line Extension design team, with assistance from WSP’s modeling team based in New York City.” Environmental Considerations Aware of the need to minimize any negative environmental impact, the design and construction team have taken measures whenever possible to create opportunities for improvements to the communities located along the new extension.


January 2023 csengineermag.com

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