Subject to the provisions of this section, nothing in this Act shall authorise a local authority without the consent of the dock undertakers concerned—
or without the consent of the railway company concerned, to execute any works along, across or under any railway of a railway company:
For the purposes of this section, dock undertakers shall be deemed to be concerned with any river, canal, dock, harbour, basin, lock, reservoir, towing path, wharf, quay or land if it belongs to them and forms part of their undertaking, or if they have statutory rights of navigating on or using it, or of demanding tolls or dues in respect of navigation thereon or the use thereof.
Nothing in this section shall be construed as limiting the powers of a local authority under any of the foregoing provisions of this Act in respect of the opening and breaking up of streets and bridges for the purpose of constructing, laying and maintaining sewers, drains and pipes.