Title - Probe reveals snag in AC rake

KOLKATA: Thursday evening's incident in which a Metro train overshot a station and then screeched to a halt 50 metres away could have been disastrous had there been more trains in the system. According to Metro Railway sources, inspection of the AC rake - the third in the series - revealed that it developed a major snag due to which the brakes refused to engage.The rake will be inspected on Saturday too and the motorman will be asked what exactly went wrong. A source claimed that while commuters wait eagerly for the AC rakes, motormen are still not too comfortable with them."Inspection revealed that there was a problem due to which the circuit which drives the motor failed to disconnect when the brakes were applied before entering Gitanjali station. This means that the motor kept on running and the train didn't slow down. There is something known as the High Speed Circuit Breaker (HSCB) in the train that acts as a safety device. Though the HSCB dropped, the circuit didn't break and the train kept on moving. This was when the driver applied emergency brakes. The momentum was so high that he overshot the platform. Though the wheels stopped rolling, they got dragged along the tracks for the next 50 metres," a source claimed.The inspection results have got officials worried. Motormen are still not completely accustomed to the automatic signals and the possibility of an error in judgement can't be ruled out. The normal speed of a Metro train is 50-55 kmph. At this speed, it takes a train about 50 metres to stop if emergency brakes are applied. The distance is reduced if the motorman brings the speed down by applying normal brakes. This is how several suicide attempts have been thwarted."Under an automatic signaling system, motormen are allowed to proceed with caution even if the signal is red and stop at a safe distance from the train ahead. Imagine a situation when a rake gets stuck midway between two stations due to a snag. What if the motorman of the train behind gets close and then tries to apply normal brakes but can't. By the time he applies emergency brakes, the two trains may be less than 50 metres apart. It is good that the officials have directed motormen not to start from a station unless the signal is green," the source added.According to Protyush Ghosh, DGMG, Metro Railway, the exact details about Thursday's incident will be known after Saturday when inquiry is complete. He, however, discounted the possibility of a risk to commuters.