The Los Angeles Metro Rail is among the world''s most technically advanced mass transportation systems. The Metro Rail subway project has presented unique types of challenges in the past, during design and construction. These included toxic gas environment due to existing oil fields; complex seismic topography and geology of the Los Angeles Basin; presence of old buried utilities and high-rise structures in urban surroundings. This paper outlines tunneling in hard rock, passing under an existing fault and through ecology sensitive areas in a canyon.
Los Angeles, having decided in the early 1980''s to join the league of World Cities that provided Mass Rail Transit to it''s citizens, faced a major challenge to create a backbone system and a series of feeder lines that would provide a network for commuting. The backbone system, located within an already established downtown and areas where the businesses were thriving, had to be placed underground to allow for the usage of streets as is for other modes of transit. The subway design by necessity had to be innovative and state-of-the-art because of the hydro-carbon gases in the ground, seismological activity of the area and a design to maximize the transit services to a greater area with the available funds. The major elements of the Los Angeles Metro Rail system include bus, rail and improvements to highway networks that will link downtown Los Angeles with the communities of the five surrounding counties. The rail network alone will consist of about 100 kilometers (km) of light and heavy (subway/tunnel) rail and regional commuter rail network with anticipated daily passenger ridership of more than 500,000 after completion in about the year 2010. Currently, more than 42 km of heavy rail (subway) designated as the Metro Red Line is either under construction or under design.