The Los Angeles County, in the state of California in the United States, was facing the issue of congested roadways due to increasing vehicular traffic. The existing multimodal transport infrastructure was facing challenges in accommodating the growing population. Therefore, the city planners came up with an alternative transportation approach, which will reduce traffic disruptions while also providing significant economic and environmental benefits. This approach involves the construction of a new Metro Rail extension, which will reduce travel time and simultaneously eliminate the need for passengers to make many transfers. The construction of this multimodal transit corridor will link the existing rail lines with three additional underground metro stations, and is expected to witness an additional commuter flow of 17,700 people daily.
The Regional Connector Transit Corridor Project is a 1.86-mile link that connects the current Blue and Expo Line terminus with the Gold Line in downtown Los Angeles. The light rail transit (LRT) corridor follows a new underground alignment (cut and cover and tunnel configurations), providing direct connections between East Los Angeles and Santa Monica, as well as between Long Beach and Azusa. The project involves constructing three new stations, including the Historic Broadway Station, Little Tokyo/Arts District Station, and Grand Av Arts/Bunker Hill Station. This USD 1.75 billion project is set to provide a one-seat ride, without transferring lines, for travel across the Los Angeles County.
The design-build transit corridor project is being carried out in three phases: third-party utility relocation, advanced utility relocation, and design/build construction. The third-party utility relocation began in December 2012. The design/build contract was awarded in the spring of 2014, leading to design finalization and mobilization of resources. The project is anticipated to be completed by 2021.
The Los Angeles County was suffering from traffic bottlenecks due to an increasing population and congested roadways. This required the city authorities to initiate an alternative transportation plan that would reduce travel times while simultaneously eliminating the need for frequent transfers. This one-seat ride feature will eventually also provide environmental and economic benefits.
The design challenges mainly revolved around preparing the plans of the three underground stations in a manner that would align with the surroundings and local environments of their respective neighborhoods. The construction of each station posed different challenges for the construction crews ─ ranging from growing high-density residential cover to difficulties in preparing underground station layouts for the stations crossing heavy rail tunnels.
The project was also exposed to certain legal challenges, in the form of environmental lawsuits claiming that the Metro’s Environmental Impact Report/Environmental Impact Statement (EIR/EIS) for the Regional Connector Transit Project did not satisfy the National Environmental Policy Act (NEPA) and the California Environmental Quality Act (CEQA).
|Client: Los Angeles County Metropolitan Transportation Authority|
|Architect of Record (AOR)||Anil Verma Associates, Inc.|
|Design-Builders||• Skanska USA Civil Western California District Inc.
• Traylor Bros., Inc.
• Hatch Mott MacDonald
|Project Advisors / Consultants||• The PFM Group – financial advisor
• Fulbright & Jaworski – counsel to the borrower
• Parsons Brinckerhoff – preliminary engineering; EIR/EIS preparation
• Metro Builders & Engineers Group – utility relocation
• Additional advisors
|Lenders||USDOT Transportation Infrastructure Finance and Innovation Act (TIFIA)|
The Transit Corridor Project made use of Bentley’s geotechnical analysis application to help design the utility network (moving the existing utilities) across the dense building foundations. The design analysis was supported with real-time settlement data linked to the city’s GPS system, enabling swift data-driven decision-making. This analysis enabled the design team to avoid soil movements and keep the excavated walls stable.
Detailed 3D models of the three underground stations were created using BIM ─ this encompassed complex mazes of equipment rooms and details on entrances and air vents leading to the surface. These 3D BIM models were complemented with the 3D printed models, which further enhanced the communication between contractors and stakeholders, inspiring cost-effective designs. An estimated USD 5 million was also saved by establishing a CDE for better coordination with over 400 consultants, contractors and stakeholders. Overall cost savings (in terms of excavation and construction) per station, ranging from USD 3 million to USD 15 million, were achieved by redesigning the initial proposals for each station.
The use of different software packages, along with 2D and 3D geotechnical analysis and 3D printed models of stations, decreased traffic disruptions during the build stage of the project. The project is scheduled to be completed in 2022.
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