Lean season mein kaafi trains mein occupancy kam ho jaati hai, toh aisi suurat main agar donon taraf se (up&down) mein occupancy kaafi kam hai toh coaches kam kiya jaa sakta hai, keep them as spare, it will be good regarding their shelf life. Ya phir frequency kam ki jaa sakti hai, eg. Metro mein peak hour mein kitni zyaada frequency hoti hai Aur phir end of the day pe frequency ghat jaati hai