in the army, you know what the driving instructor taught us? if
accelerator fail, brakes fail,
you pull the handbrakes. if the driver indeed stick to this
basic protocol, and at the speed the bus going even if the brakes
or accelerator fail, the handbrake if indeed used gensuinely would
be damaged.
all these evidence can be found after the accident atthe site
scene invesitagtion or tow back to garage for overhaul /inspection
review.
if the damages are assessed not to the depth of engine and at
the brake mechanism line assembly level, and if the brakes found
internally dmaged not due to impact but rather wear at force speed
angagement, then the driver probably telling the truth.