Paragraph 40 I1

If any permanent or temporary alterations or additions to railway property, or any protective works under paragraph 36(5), are reasonably necessary during the construction of a specified work, or during a period of 12 months after the opening for public use of any part of the authorised development that includes a specified work, in consequence of the construction of that specified work, such alterations and additions may be carried out by Network Rail and if Network Rail gives to the undertaker reasonable notice of its intention to carry out such alterations or additions, the undertaker must pay to Network Rail all costs reasonably and properly incurred in constructing 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 Network Rail in maintaining, working and, when necessary, renewing any such alterations or additions.

If during the construction of a specified work by the undertaker, Network Rail gives notice to the undertaker that Network Rail desires itself to construct that part of the specified work which in the opinion of the engineer is endangering the stability of railway property or the safe operation of traffic on the railways of Network Rail then, if the undertaker desires that part of the specified work to be constructed, Network Rail must assume construction of that part of the specified work and the undertaker, regardless of any such approval of a specified work under paragraph 36(1), must pay to Network Rail all reasonable expenses to which Network Rail may be put and compensation for any loss which it may suffer by reason of the execution by Network Rail of that specified work.

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 is to be set off against any sum payable by the undertaker to Network Rail under this paragraph.