SAN FRANCISCO, Calif. — A driver drove into a MUNI Metro subway tunnel early Thursday, stalling his SUV about half a mile down the tracks, triggering a mass transit nightmare for San Francisco commuters. Scott Mitchell, 40, of Sebastapol, was arrested on suspicion of driving under the influence, driving on train tracks and failure to obey a traffic sign, San Francisco police Officer Albie Esparza said. Muni spokesman Paul Rose says an SUV entered a tunnel on Church Street shortly after 6 a.m. Thursday and drove eastward almost to the Van Ness Station. The driver stopped when the SUV...