SYDNEY (AP)-- Transport problems at the Sydney Olympics intensified Wednesday when more than 50 drivers quit the Olympic bus service, saying they were angry about working conditions and poor organization of timetables.

 A driver, who did not want to be named, said up to 50 drivers failed to turn up to work Wednesday morning, claiming the stress of providing the service was not worth the effort.

 The Transport Workers' Union has called for urgent intervention from Olympic transport organizers after drivers complained about schedules, a lack of meal breaks and rostering.

 The Olympic Road Transport Authority employed on Tuesday an additional 10 management people to resolve the driver's concerns, but a union spokesman said at least 50 drivers were believed to have quit on Wednesday.

 Meanwhile, Australian Olympic team officials urged athletes to show patience with transport delays despite admitting some problems were "unacceptable."

 A Wednesday meeting of team chefs de mission was told of several incidents affecting athletes Tuesday, including the Australian gymnastics team which was stranded for 90 minutes waiting to get to and from training.

 Australian deputy chef de mission Michael Wenden said one overseas boxing team waited as its designated driver drove past smiling and waving, mistaking the team's efforts to hail down the driver for a friendly greeting.

 On Tuesday, British archer Simon Needham suffered minor facial injuries when one bus struck another in the Olympic Village -- the latest in a string of accidents that have hit the Olympic transportation system in the days before the games begin.

 One of the most attention-getting breakdowns took place last weekend, when IOC president Juan Antonio Samaranch cancelled a tour of the International Broadcast Center because a bus failed to show at his hotel.