8U.K.The appropriate authority shall not, without the consent of the highway authority, construct any part of the works authorised by this Act under and within 8 metres of the surface of any highway except in accordance with plans and sections submitted to, and approved by, the highway authority and if within 28 days after such plans and sections have been submitted the highway authority have not approved or disapproved them, they shall be deemed to have approved the plans and sections as submitted.