8(1)If any alteration or addition, whether permanent or temporary, to railway property shall be reasonably necessary during the construction of the specified works, or during a period of twelve months after their completion in consequence of their construction, such alterations and additions may be carried out by the Railways Board.
(2)If the Railways Board give to the Secretary of State reasonable notice of their intention to carry out such alterations or additions, he shall pay to the Railways Board the reasonable cost of the alterations or additions including, in respect of permanent alterations and additions, a capitalised sum representing any increase in the costs which may be expected to be reasonably incurred by the Railways Board in maintaining, working and, when necessary, renewing any such alterations or additions.
(3)If the cost of maintaining, working or renewing railway property is reduced in consequence of any such alterations or additions, a capitalised sum representing such saving shall be set off against any sum payable by the Secretary of State to the Railways Board under this Part of this Schedule.