This article reviews two of the major challenges on the metro rail project in Los Angeles, and summarises the engineering solutions that have been adopted to meet them. The metro rail project was proposed and launched by the southern California rapid transit district (sctrd). Its first stage, a 7 km (4.4 mile) five-station minimum operating segment (mos-1) in central Los Angeles, is expected to go into service in 1992. The two challenges discussed here are: (1) seismic modelling and design of underground structures; (2) construction in gassy ground. Two levels of earthquake were considered: (1) the 'operating design earthquake', with approximate richter magnitude 6.5 and approximate probability 0.5 of being exceeded during a 100 year design life; (2) the 'maximum design earthquake', with approximate richter magnitude 7.0 and approximate probability 0.05 of being exceeded during this period. Finite element analyses and computer design calculations showed the validity of the design goal adopted: to provide sufficient ductility to absorb the imposed deformation, without losing the capacity to carry static loads. The scheme adopted for protecting mos-1 against gas was: (1) wrap all underground structures with a 100-mil membrane of high density polyethylene; (2) provide a system of sensors for continually monitoring the amount of gas in the air; (3) provide emergency ventilation, to be activated if gas levels begin to rise. Current plans are to continue with these solutions, but remain alert to improvements in seismic design and handling of gassy tunnels.

  • Availability:
  • Corporate Authors:

    Mining Journal Limited

    60 Worship Street
    London EC2A 2HD,   England 
  • Authors:
    • MONSEES, J E
  • Publication Date: 1988-3


  • English

Media Info

  • Pagination: p. 68-73
  • Serial:
    • Volume: 1
    • Issue Number: 1
    • ISSN: 0956-8700

Subject/Index Terms

Filing Info

  • Accession Number: 00487484
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Files: ITRD, TRIS
  • Created Date: Sep 30 1989 12:00AM