Paragraph 55 I1

If any alterations or additions, either permanent or temporary, to railway property are reasonably necessary during the a period of 12 months after the new tunnel is opened to traffic, in consequence of the construction of a specified work, and Nexus gives to the undertaker reasonable notice of its intention to carry out any such alterations or additions specifying the alterations or additions to be carried out, the undertaker shall pay to Nexus the reasonable cost of those alterations or additions including, in respect of any such alterations and additions as are to be permanent, a capitalised sum representing the increase of the costs which may be expected to be reasonably incurred by Nexus in maintaining, working and, when necessary, renewing any such alterations or additions.

The engineer shall, in respect of the capitalised sums referred to in this paragraph and paragraph 56(a), provide such details of the formula by which those sums have been calculated as the undertaker may reasonably require.

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 undertaker to Nexus under this paragraph.