San Francisco Municipal Transportation Agency (SFMTA) says that measures taken to reduce the spread of the Covid-19 pandemic have pushed back the date passengers will be able to use the line. Since many of the workers in the tunnel have to work close to one another, three separate coronavirus outbreaks forced quarantine periods. Delivery of materials and equipment was also slow due to the pandemic restrictions.

SFMTA says additional delays have resulted from design changes due to differing site conditions in the underground sections of the project.

The cost of the project has risen from $US 1.5bn to $US 1.6bn, with further spikes in cost expected due to the pandemic.

Construction may be finished by March 2021, before the tunnel is handed over to transport operator San Francisco Municipal Railway (Muni) for at least a year of testing. SFMTA was previously planning for a mid-2021 opening date, before delaying to the end of 2021 earlier this year.

The Central Subway will run from downtown San Francisco to Chinatown, running from 4th and King Street station, via 4th and Brannan, Yerba Buena/Moscone, Union Square/Market, Chinatown, to North Beach/Washington Square. The line includes both at grade and underground sections.

Two other major setbacks have occurred over the last 10 years. A conflict with a contractor and poor soil conditions caused one delay. Another problem occurred when a subcontractor installed the wrong rail.

Construction is about 97 percent complete, with SFMTA saying that the majority of at-grade work now complete. The last closed street - a section of Washington Street in Chinatown - will reopen by the end of the year. The remaining work is underground.

For detailed data on metro projects from around the world, subscribe to IRJ Pro.