While a loose screw or two may be just a matter of carelessness for an individual, it can prove catastrophic for an organisation like Central Railway (CR) that caters to lakhs of people every day through its elaborate infrastructure. Sources say that a loose fitting may have caused the tragic death of three commuters yesterday on a Chhatrapati Shivaji Terminus (CST)-bound fast train. Apparently a screw of a fitting done to support the inspection platform of a signal pole jutted out, thus resulting in people hitting the exposed portion and falling out of a moving train. The platform is used by workers for maintenance of the signal, and to change or clean bulbs.