§ Mr. Peter Bottomley
To ask the Secretary of State for Transport what assessment has been made of the length of time it will take to renew existing British Rail bridges,864W trains, signalling and power supply equipment at the present rate of replacements; and what information he has on the average design life of each category or main type of (a) bridge, (b) train, (c) signalling and (d) power supply equipment.
§ Mr. Freeman
An assessment of this kind would not yield meaningful results given the varied durability of the different assets mentioned. The design life of bridges varies from 20 years to more than a century, of trains from 25 to 40 years and for signalling and power supply equipment from 20 years upwards. Asset lives assumed for the purpose of calculation of amortisation and depreciation charges in British Rail's annual report and accounts for 1991–92 are set out in note 4 on accounting policies in that report.