If any alterations or additions, either permanent or temporary, to railway property shall be reasonably necessary during the construction of the specified works, or during a period of 12 months after the completion of those works, in consequence of the construction of the specified works, such alterations and additions may be carried out by Railtrack PLC and, if Railtrack PLC gives to the Company reasonable notice of its intention to carry out such alterations or additions, the Company shall pay to Railtrack PLC the reasonable cost thereof including, in respect of permanent alternations and additions, a capitalised sum representing any increase in the costs which may be expected to be reasonably incurred by Railtrack in maintaining, working and, when necessary, renewing any such alterations or additions.