Although BART trains were not picking up passengers Friday, a limited number of trains are running along the system for maintenance and security reasons, a BART spokeswoman said.
The trains are running to make sure the tracks do not rust and everything is in working order, BART spokeswoman Luna Salaver said.
"The trains are running around the system to keep the tracks in good shape," Salaver said. She advised passengers who see trains working to not falsely expect to hop on. Salaver said keeping the system active also helps with security.
Usually with trains cruising throughout the system, there is "an extra pair of eyes" monitoring BART property, she said.
With the work stoppage, parts of the system that are usually bustling are empty and therefore more vulnerable to security breaches, Salaver said.
She said all maintenance and security work is being performed by a small group of non-union staff members.