Like it or not, it is time to implement security screening and to install detectors at all MRT stations.
This may cause a little inconvenience, but, for the sake of protecting lives and properties, and to ensure continuing train service, such moves are of paramount importance.
Just checking suspicious bags randomly cannot guarantee safety, given that more attacks are happening in other parts of the world, despite increased camera surveillance.
When my wife and I travelled by train from Marriott hotel in Beijing to the Wangfujing shopping area, we had to pass through security screening and detectors at the entrance to the train station.
All bags (big or small) had to be screened. The process was efficient and fast, without giving rise to long queues.
Sim Beng Tiong