The Yuba City bus disaster occurred on May 21, 1976 in Martinez, California. A 1950 Crown bus operated by Student Transportation Lines, Inc. had been chartered to carry the Yuba City High School a cappella choir from Yuba City to Miramonte High School in Orinda for a friendship day involving the choirs of the two schools. The accident occurred at 10:55 a.m., as the driver took the Marina Vista (exit 56) off-ramp from I-680 southbound from the Benicia–Martinez Bridge. The driver was unfamiliar with this bus, and mistakenly thought the low air pressure warning (for the air brakes) was a warning of low engine oil pressure. The driver left the freeway at the aforementioned off ramp, and the brakes failed due to lack of air pressure. The bus struck and mounted the bridge rail and left the eleva