k) Intangible assets
These assets mainly comprise of concession rights. Intangible assets acquired separately are capitalized at cost and those from business combinations are capitalized at fair value as at the date of acquisition. Following initial recognition, the cost model is applied to intangible assets. The useful lives of these intangible assets are assessed to be either finite or indefinite. Intangible assets with finite lives are amortized over the useful economic life. Intangible assets with an indefinite useful life are reviewed annually to determine whether the indefinite life assessment continues to be supportable. If not, any changes are made on a prospective basis.