12. Investment property (in millions of euros)Total real estateComposition per 1 January 2015 Cost292Cumulative depreciation and impairments-96Carrying amount as at 1 January 2015196 Changes in 2015 Additions8Depreciation-8Divestments-2Impairment- Reversal impairment- Other changes- Total changes-2 Composition per 31 December 2015 Cost295Cumulative depreciation and impairment-101Carrying amount as at 31 December 2015194 Changes in 2016 Additions1Depreciation-9Divestments- Impairments-2Reversal impairment- Other changes13Total changes3 Composition per 31 December 2016 Cost306Cumulative depreciation and impairments-109Carrying amount as at 31 December 2016197The other changes in 2016 relate to the transfer from other asset categories to investment property.Given the nature, diversity and locations (station environments) the fair value of the property portfolio can not be determined reliably. Is expected to be the fair value substantially higher than the book value of the properties.The properties exist alongside commercial properties also of other real estate properties that are leased to third parties or held as strategic real estate. The leases include a period of several years in which cancellation is not possible. Thereafter, a negotiation about extension with the tenant will take place. The total contractual rent until the end of the leases amounts to approximately € 200 million in 2016. No contingent rents are charged.The direct rental income was €68 million (2015: €55 million). The direct rental costs are maintenance costs, property taxes and direct management costs, coming to a total of €19 million (2015: €16 million).