Depreciation useful life rules require adherence to Schedule II with disclosure and technical justification for deviations. Schedule II requires application of Part C useful lives and a limited residual value, with mandatory disclosure and technical justification for any deviation; prescribes a revenue based amortisation method for concessionary intangible road assets with annual adjustments to projected revenue; mandates regulatory or government notified useful lives where applicable; and sets rules on componentisation, pro rata calculation for additions and disposals, shift based increased depreciation, and transitional treatment of carrying amounts.