Problems that constructors have had to overcome in their design and construction of the Southern California Rapid Transit District's (RTD) $3.75-billion, Metro Red Line in Los Angeles are described. Line segments are being constructed by tunnel boring machines and crossovers are excavated by cut-and-cover techniques. The area sits atop oil and abondoned natural gas wells; the quantification and management of the uncharted presence of hydrocarbons is described. Besides the extensive monitoring, contractors are required to use explosion-proof equipment in mining operations and to install ventilation systems that will provide an air velocity of 100,000 cu ft per minute during construction. A central gas monitoring system developed expressly for the Red Line will be installed to measure methane gas and hydrogen sulfide. A 100-mil thick, high density polyethylene (HDPE) membrane is being used to encapsulate the tunnels and stations. Construction has been slowed by large boulders. The design also accounted for a moderate-scale earthquake expected within 100 years; the structure was made ductile by adding 5 to 10% more reinforcing steel to tunnel joints to absorb the imposed deformation. Other seismic design criteria are also noted. The construction involved the moving of a great number of utilities, remedying leakages, and cleaning asbestos used to insulate utilities. A unique vertical conveyor was used to move muck to a truck-laoding bin 46 ft above street level. The protection of downtown buildings from settlement after tunnel excavation is described. A carefully orchestrated traffic control plan that maintained traffic flow above ground is noted.

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  • Corporate Authors:

    McGraw-Hill, Incorporated

    330 West 42nd Street
    New York, NY  United States  10036
  • Publication Date: 1989-6-8

Media Info

  • Pagination: p. 38-43
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00485150
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Jun 30 1989 12:00AM