Vote on S.F. school bus provider complicated by accusation of corporate espionage FacebookTwitterEmail 1of3 A school bus driver takes students home from Hillcrest Elementary in San Francisco.Mike Kepka / The Chronicle 2011Show MoreShow Less 2of3 Children disembark arrive for school at Alice Fong Yu K-8 School in San Francisco.Lea Suzuki / The Chronicle 2010Show MoreShow Less 3of3 San Francisco school officials plan to vote Tuesday on a proposal to end 40 years of bus contracts with First Student Inc. and choose a new provider, Zum Services, whose consultant recently left a top job with First Student and downloaded its competing bid into his email account while joining its rival.