California Department of Transportation
Coronado Bridge Carquinez Bridge San Francisco/Oakland Bay Bridge Richmond San Rafael Bridge

Materials Engineering and Testing Services

Office of Roadway Materials Testing
Electrical Testing Branch


Program Overview:

In light of recent rolling blackout experienced in the State of California and the recent retrofitting of all intersections from incandescent traffic signals to LED traffic signals, it is now feasible to backup the entire intersection for a period in excess of 2 hours. •Each BBS will enable the intersection to continue operating normally for periods in excess of 2 hours by converting DC battery voltages into AC line voltages.  This was not feasible until the introduction of LED’s into traffic signals.

Testing of BBS:

Design fit – Will the BBS fit into an existing 332L Cabinet with no modifications.  This is important in order to retrofit existing intersections.

Battery Life – Will the system back up an intersection for a minimum of 2 hours and then be fully recharged and prepared for another 2 hours of operation in under 24 hours.

Environment – Can the system operate normally in harsh conditions. -37ºc to +74ºc and 20% to 95% humidity.


Specification for Battery Backup System (BBS)  dated 7/09
Supercedes 7/04 Specification
TEES 2009 Errata No. 1  dated 1/2010

Contact:, Transportation Engineer (Electrical)
Fax (916) 227-7026