Raising the Bar of BART

Dunn, James; Horton, Thomas; Wu, Ching; Hughes, William; ,

Raising the Bar of BART

by James Dunn, Chief Engr.; Bay Area Rapid Transit District, Oakland, CA,
Thomas Horton, Proj. Mgr.; Bay Area Rapid Transit District, Oakland, CA,
Ching Wu, Proj. Mgr.; Bechtel/HNTB Proj. Team, Oakland, CA,
William Hughes, Engrg. Mgr.; Bechtel/HNTB Proj., Oakland, CA,

Serial Information: Civil Engineering—ASCE, 2001, Vol. 71, Issue 12, Pg. 60-65

Document Type: Feature article

Abstract:

Although it was originally designed to withstand a strong earthquake, and did so admirably in 1989, the Bay Area Transit (BART) system was recently evaluated to determine its ability to stand up to an even stronger seismic event that might be generated by the many faults that surround it. The components analyzed included aerial structures; aerial, at-grade, and underground stations; cut-and-cover boxes; U-walls; and steel-lined tunnels. The study also looked at electrical and electronic systems, ancillary structures, and secondary hazards such as fires, floods, or other difficulties caused by forces outside the BART system. The design team's retrofit recommendations for the aerial structures and guideways address foundation strengthening through additional top mat reinforcement, added piles (both cast-in-drilled-hole and micropile options), and column jacketing using either steel or fiber reinforcement to protect against joint shear. The underground stations require only minor strengthening of girders and columns. To deal with the soil conditions surrounding the San Francisco ventilation structure, the team is considering either soil improvement through soil mixing or jet grouting, placing a barrier wall adjacent to the structure, or anchoring the structure with piles.

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