At the unveiling of Muni's new buses Monday, one of the biodiesel-electric hybrid vehicles hit a bump in the road with the mayor aboard before it even, well, got on the road.
Mayor Ed Lee and other city officials had touted the buses at a news conference at Pier 48 near AT&T Park and then hopped on board one of them with the intention of going to City Hall.
However, the bus could not be driven, and the mayor and the rest of the group were ushered into another bus.
Crews were initially looking at the bus's hydraulic system as the source of the problem, but later determined that a sensor was incorrectly showing that the rear door of the vehicle was open, which prevented the bus from driving away, Muni spokesman Paul Rose said.
The problem has since been resolved and crews will check the rest of the new buses to make sure similar issues don't pop up, Rose said.
The vehicles are part of a fleet of 62 new hybrid buses being introduced into the Muni system starting this week. Muni has not had any new buses since 2007, agency officials said.
San Francisco Municipal Transportation Agency Transportation Director Ed Reiskin said the buses will provide "a smoother, nicer ride" and "really represent a significant investment in transit."
Lee said the buses are "greener and cleaner" than previous Muni buses and will help shuttle riders to various large events taking place in The City this summer, including the America's Cup sailing races and concerts in Golden Gate Park.
The new buses, which cost about $752,000 each, are being paid for with federal, state and local funding and will replace 13-year-old buses currently in service, Muni officials said.