The DfT states that their involvement in a future fleet specification and acquisition is necessary for several reasons. Though Britain's rail operators are privatised, their franchises seldom last for more than 12 years; a train, on the other hand, may remain in service for more than 30 years. It is therefore entirely unprofitable for the franchise operator to replace the fleet, leaving the only other option to hire newly acquired trains from third parties, which can prove extremely expensive. The DfT also states that it can, and has, brought train operators together with a `whole system, whole life' perspective to decide on a specification that will be more flexible with regards to future routes and fleet transfers as well as more environmentally aware.