From a source -
At about 3pm at Tampines Interchange today, one of the Sv 291
drivers didnt leave on time. One of the control officers went to
talk to him and they somehow got into an argument. The driver
refused to leave and his bus was stuck next to the Sv 291 berth,
jamming other buses and leading to long lines. There were lines of
Sv 38, Sv 29, Sv 19 etc etc buses piled up, unable to leave because
of the stupid bus jamming their way. Finally they managed to get
the bus away and normal operation resumes. Only one half of the
interchange was affected, the other half (with 67, 10, 22, 969 etc)
was unaffected.