6/25/2014
Joe Raedle/Getty Images

Big Alma and Mom Chung have completed their 1.7-mile tunneling journey as part of San Francisco's $1.6 billion Central Subway project. The tunnel-boring machines excavated and built a pair of concrete-lined tunnels on time and within budget, according to John Funghi, project manager for the subway. The new line is expected to open in 2019.

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