Los Angeles Metro Gold Line Eastside Extension

Client

Los Angeles County Metropolitan Transportation Authority, Los Angeles, Kalifornien, USA

Contractor

Traylor Frontier Kemper Joint Venture
Consultant:
BeMo Tunnelling as Consultant for NATM-Cross-passages: Design-input for NATM-Crosspassages between TBM-Metro-Tunnels, Consulting and Technical support, Know how Transfer, SEM/NATM Tunnel Engineer and SEM/NATM Tunnel Specialist Operators on site

Project location

Los Angeles, Kalifornien, USA

Start of construction

2005

End of construction

2007

Project total value

approx. 0.5 million €

Geology

Alluvium, non-homogeneous sediment layers, medium dense clays to loose silts and sands, layer thicknesses 1-20 ft (0.3 6.1 m), methane gas, hydrogen, sulfide and methanol, up to 1.5 bar of hydrostatic pressure

Technical Data

• Know-how-Transfer Project of the New Austrian Tunnelling Method (NATM) for the construction of NATM-Crosspassages between segmentally lined twin tunnels
• 6 Crosspassages: each approx 36 – 38 ft (11 – 12 m)
• Cross-section: 242.63 – 283.48 SF (22.54 – 26.34 m²)
• Excavation by excavator under pipe arch (pipe roofing), installation of “hamster cages” in both tunnels
• Execution by SEM/NATM

Further project related information

• Excavation 49.21 ft (15 m) below ground level
• Sequential excavation in 3 – 9 ft (0.91 – 2.74 m) increments, top-heading, bottom-bench under pipe arch (pipe roofing), installation of “hamster cages” in both tunnels
• Most crosspassages are located under the water table, and up to 1.5 bar of hydrostatic pressure