 Phase III will have 28 underground stations covering 41 km . More than 20 tunnel boring machines are expected to be simultaneously used during construction of Phase III . Delhi Metro is expecting a ridership of 4 million after completion of Phase III . DMRC has decided to use communication based train control ( CBTC ) for signalling which will allow trains to run at a short headway of 90 seconds . Keeping this in mind and other constraints , DMRC changed its decision to build 9 car long stations for new lines and instead opting for shorter stations which can accommodate 6 car trains . 
