before the start of service, a maintenance vehicle leaked oil onto the tracks from buona vista mrt station to clementi mrt station until the junction with ulu pandan depot. the first 10 westbound trains reported braking difficulties. the eleventh train, a c151, had to use its emergency brakes to stop at the station. at 7.50 am on 5 august 1993, the 12th train, another c151, collided with the stationary c151 at clementi while it was recharging its batteries, resulting in 156 injuries.