While the cause was clear - that there was a particular signal interfering with the trains' wireless signalling system - tracking it down required a lot of "effort" because they needed to eliminate the various possibilities one by one to establish the cause, he said.
The LTA also published fresh figures on the rail service performance of various lines on its website yesterday.
In the first half of the year, there were 10 MRT train delays of more than 30 minutes, compared with 15 for the whole of last year. Four of these took place on the East-West Line, three on the North-South Line, two on the Circle Line, and one on the North-East Line.
In addition, there were eight service delays of more than 30 minutes on the LRT network - five of them on the Sengkang-Punggol network - compared with 15 for the whole of last year.
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