BART In Earthquake Conditions

BART teams with UC Berkeley to adopt earthquake early warning system
Thanks to assistance from the Berkeley Seismological Laboratory, the San Francisco Bay Area Rapid Transit system can now automatically brake trains when earthquakes threaten to rattle the Bay Area, allowing perhaps tens of seconds to a minute for trains to slow down before the ground starts to shake.

Instituted last month, the earthquake early warning system was created with the help of University of California, Berkeley, seismologists who hooked BART into data flowing from the more than 200 stations of the California Integrated Seismic Network throughout Northern California.

Electronic signals from seismic stations travel much faster than seismic waves. For quakes outside the Bay Area, these data give BART’s central computers advance notice that shaking is on the way; for quakes in the Bay Area, it provides more rapid warning. If the messages from the seismic network indicate ground motion above a certain threshold, the central computers, which supervise train performance, institute what BART calls “service” braking, which is a normal slowdown to 26 miles per hour.

The farther the quake from the Bay Area, the more time trains have to slow from speeds up to 70 mph.

“The earthquake early warning system will enable BART to stop trains before earthquake shaking starts and thereby prevent derailment, and save passengers from potential injuries,” said BART Board President John McPartland. “We are the first transit agency in the United States to provide this early warning and intervention.”