yes agreed, not everytime AND not everywhere train is clean and punctual. ISO certification means, if this train got lot then controllers as well as zone need to provide answer when the ISO certification will be renewed. and ISO certification gives a train high priority with monitoring in control system.
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For cleaning you just need to send a sms to IR and at next big stn it will be cleaned. so facilities provided to ISO trains are much better then normal.
Also...
more... this train runs jam-packed round the year, maintenance of it is a very very difficult task.