A state appeals court has reinstated a suit against San Francisco by a woman who broke her leg while getting off a Muni bus.

Nicole Nunn accused the driver of violating the Municipal Railway's written guidelines, which require drivers to pull buses within a foot of the curb during stops unless parked cars are in the way. The guidelines also require drivers to use the "kneeler'' that lowers the front end of the bus at a passenger's request or whenever it would aid in boarding.

According to Nunn's suit, the northbound 47 Van Ness bus on which she was riding in December 2000 stopped one lane away from the curb at Van Ness Avenue and Sutter Street. Nunn, then 25 and on her way to a computer training class, broke her fibula when her foot hit the pavement, then fell and hurt the ankle of her other leg.

She said there were no cars or other obstructions that would have prevented the driver from pulling closer to the curb. Nunn, who stood 5 feet 2 and weighed 265 to 270 pounds, did not ask the driver to use the "kneeler'' but offered medical evidence that she wouldn't have broken her leg if the device had been used or if the bus had pulled up to the curb.

Her damages suit was joined by an insurance company that paid her workers' compensation benefits and sought reimbursement from the city. Superior Court Judge Paul Alvarado dismissed the suit, accepting the city's argument that the driver had acted safely by letting passengers off on smooth pavement away from traffic. But the appeals court said the safety issue should go to a jury.

"It is for the jury to decide if the operator's failure to pull the bus to an unobstructed curb at the regular bus stop and the additional failure to kneel the bus, in light of (Nunn's) physical condition, violated the standard of care,'' said Justice Mark Simons in the 3-0 ruling, made public Tuesday.

Gerald Clausen, an attorney for Nunn, said the ruling reflected the legal obligation of transportation agencies to "exercise the utmost care for the safety of their passengers."