questionText: To ask the Secretary of State for Transport, pursuant to the Answer of 14 January 2026 to Question 102105 on Network Rail: Assets, what assessment she has made of the effectiveness of Network Rail’s calculation of the Composite Sustainability index for each railway asset; and what assessment she has made of rail asset (a) age and (b) condition in (i) Control Period 4 (ii) Control Period 5 (iii) Control Period 6 and (iv) Control Period 7.
answerText: The methodology for the composite sustainability index (CSI) calculations is developed by Network Rail and is recognised by the regulator, the Office of Rail and Road, as being a reliable and effective means to monitor the changing remaining life of railw...
heading: Network Rail: Assets