It happened around 1:30 p.m. near G Street and Divisadero. Police say she was standing near the track and walked in the path of the oncoming train.
She was swept under for about 700 feet before popping back out along the tracks. The woman suffered a broken arm and other possible fractures to her body but is expected to be okay.
Police say she told them she was mistaken for what track the train was on when she was hit.