Work was being performed in two shifts when the 1906 San Francisco earthquake struck in April . Workers in Tunnel 3 ( below the orphanage ) were terrified by the shaking , which extinguished the lamps they were using , but no one was injured and the tunnel was not damaged . After the earthquake , construction continued . Earthquake survivors were unnerved by blasting for the tunnels , which they thought were aftershocks . Some of the areas for the Bayshore Cutoff route south of China Basin were filled with rubble from the earthquake , allowing more rapid progress than planned . SP officials announced in August 1906 the estimated completion date for the Bayshore Cutoff would be January 24 , 1907 . Once the Cutoff was in place , they stated that more frequent service would be offered for commuters , with headways of 30 minutes and total travel time to San Jose estimated at one hour
1906 San Francisco earthquake
1906 San Francisco earthquake
Bayshore Cutoff