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NEW DELHI: With over 2 lakh litres of water being used every day, the depot at Khyber Pass in north Delhi may well be one of the most watered areas in Delhi. All that water is recycled for irrigation, say Delhi Metro officials. As you walk into the depot late at night, though, it's the meticulous maintenance work going on that first strikes you. As a maintenance and safety official of Delhi Metro Rail Corporation says, the trains are the much-monitored babies, not left alone for a single minute. "At every stage of operation and maintenance, the train is under someone's charge...no one without proper authorization is allowed to enter it," says Mangu Singh, managing director, DMRC.

Considering the Rs 80 crore tag, it is not surprising that the coaches are so jealously guarded. The train goes through physical checks every day, along with constant monitoring by a team of professionals, so that opera- t i o n schedules can be maintained and the train doesn't stop in the middle of the track. "Two teams keep a constant watch—the PPIO and those in the operations control centre," says the Delhi Metro official. The PPIO is the planning, progress and investigation organization at the depot, which keeps the schedule of the train maintenance as well as does a physical check every day, based on a pre-determined schedule. The third layer of checking is done by the train operator (TO), who not only gauges the operational running but also keeps an eye out for anything that requires a closer look once in the depot.

In fact, the constant exchange of data be-tween the PPIO and the OCC determines the maintenance plan of the train at the depot. The maintenance is broken up into parts: the under-frame, the interiors and the roof. "It's not just scheduled maintenance. We also do active, preventive maintenance," adds the official. The basic check is done every day at the depot. If a problem is detected, it goes into the IBL or the workshop, depending on the snag. If the train is going into revenue service without any major maintenance being planned, it only goes through a routine cleaning. If a thorough cleaning is scheduled —which is done every three days—then it will go through the automated washing process. The schedule is rigorous, say Delhi Metro officials. "The train runs approximately 400km every day, so maintenance is extremely important," he adds. There are three-day, 15-day, 45-day, 3-monthly, 6-monthly and annual schedules. In the basic mode, safety features of the under-frame, horn, wipers, headlights and announcement systems are checked. After every 15 days, cleaning and measurement of the roof, the under-frame and interior features is the norm. The 45-day maintenance schedule includes cleaning, measurement, monitoring and part over-hauling. The rest of the activities like replacement of oils are scheduled in the later maintenance. The annual schedule is the most exhaustive, as by that time, the train has travelled more than a lakh kilometres. Maintenance of the wheels and the brakes is an important part of the schedule. The train is divided into the motor car and the driving trailer, both of which form a unit. The wheels on the DT need to be changed every eight-nine months while those of the motor car last 15-16 months. Similarly, the brakes on the DT need to be changed every 45 days while those on the motor car last five months.

The roof is also a delicate part and needs to be cleaned every 45 days. "The pantograph on the roof has a carbon coating, which sees regular wear and tear every day. To get rid of the carbon residue, the roof needs to be cleaned, so that corrosion does not occur," explained the official.