If by the end of the period of 56 days beginning with the date on which such plans have been supplied to Network Rail, Network Rail gives notice to the Promoter that Network Rail desires itself to construct any part of the specified works which in the opinion of the engineer will or may affect the stability of railway property, the safe operation of traffic on the railways of Network Rail or the services of train operators using the same then, if the Promoter desires such part of the specified works to be constructed, Network Rail shall construct it with all reasonable dispatch on behalf of, and to the reasonable satisfaction of, the Promoter in accordance with the plans approved or deemed to be approved or settled as aforesaid.