The London Underground (East London Line Extension) (No. 2) Order 2001

8.  Upon signifying his approval or disapproval of the plans the engineer may specify any protective works, whether temporary or permanent, which in his opinion should be carried out before the commencement of the construction of the specified works to ensure the stability of railway property, the continuation of safe and effective operation of the railways of the Company or the services of operators using those railways (including any relocation of works, apparatus and equipment necessitated by the specified works) and the comfort and safety of the passengers who may be affected by the specified works, and such protective works as may be reasonably necessary for those purposes shall be constructed by LUL with all reasonable dispatch, or, if LUL so desires, such protective works shall be carried out by the undertaker at its own expense and the undertaker shall not commence the construction of the specified works until the engineer has notified the undertaker that the protective works have been completed.