Construction-in-progress represents buildings, tracks, bridges and service roads under construction, and mainly includes the construction related costs for the associated facilities of the existing railway lines of the Group. Construction-in-progress is stated at cost, which includes all expenditures and other direct costs, site restoration costs, prepayments attributable to the construction and interest charges arising from borrowings used to finance the construction during the construction period, less impairment loss. Construction-in-progress is not depreciated until such assets are completed and ready for their intended use. From time to time, certain railway assets of the Group require major modifications and improvements. The carrying amounts are transferred from fixed assets to construction-in-progress. The carrying amounts, including costs of modifications, are transferred back to fixed assets upon completion of the improvement projects.