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Bay Area Rapid Transit June 3 announced findings of a year-and-a-half-long study designed to help the transit system prepare for a major earthquake. Although the 30-year-old system survived the 1989 Loma Prieta earthquake nearly unscathed, U.S. Geological Survey statistics indicate there’s a 70 percent likelihood that a major earthquake could hit the Bay Area before 2030 and system improvements must be made, said BART officials in a prepared statement.



Following the Loma Prieta earthquake, BART conducted eight seismic studies and five retrofitting projects as part of its seismic retrofit program. The current Seismic Vulnerability Study, conducted by Bechtel/HNTB, is the most comprehensive evaluation of BART’s facilities since the system was constructed. In it, evaluators concluded that the transbay tube be given priority.



When the tube was constructed prior to BART’s 1972 opening, it was considered an engineering marvel, said BART Chief Engineer Jim Dunn.



But the study recommends it be strengthened primarily because of what geologists now know about how certain soils can liquify during earthquakes. It concludes that, although researchers aren’t sure exactly how liquified soil might affect the tube, a worst-case combination of events could cause excessive motion of the seismic joints and structural stress along the tube, resulting in significant damage.



Of the several options offered, the study recommends BART adopt a $1.1 billion systemwide retrofit program that’ll take more than a decade to complete. BART management already is aggressively pursuing local, state and federal funds.



"BART is the backbone of the Bay Area’s transportation network, and, as demonstrated in 1989 when the Bay Bridge failed, BART’s ability to maintain service after a major earthquake is essential to avoid gridlock and keep the region’s economy on the move," said BART General Manager Thomas Margro.