Services of Kowloon Motor Bus were disrupted on Monday morning after a breakdown in the company’s computerised rostering system for drivers.
Photos circulated on the internet showed dozens of bus drivers waiting in long queues at depots for their rosters.
A representative of a KMB staff union, Lee Kwok-wah, said some drivers couldn’t find the buses they were supposed to drive because of the glitch.
He said the computer system provided the drivers with information such as the bus routes they are supposed to take and where the buses are parked.
But all this information needed for the drivers to start their shift had to be done manually because of the system failure, causing a lot of confusions and bus delays.
Hundreds of passengers waited at a bus stop at Tuen Mun at one point as buses were delayed.
The Transport Department said it had been notified about the incident, and it urged other public transport operators to strengthen their services.
KMB apologised for the glitch.