SINGAPORE - The SMRT train collision on Wednesday morning (Nov 15), which saw 25 people injured, was the second such incident in the MRT's 30-year history. In August 1993, a damaged rubber ring set off a chain of events that led to the collision between two trains at Clementi MRT station, leaving about 160 passengers injured. The ring broke, causing 50 litres of oil to drip onto the tracks from a locomotive doing maintenance during non-passenger hours.