In so far as they authorise the execution of any works on, over, under or to, or the exercise of any powers in relation to, any highway not forming part of the bridge, the powers conferred on the Authorities by this Act shall not be exercised without the consent of the highway authority.

Any consent requested for the purposes of subsection (1) above shall not be unreasonably withheld but may be given subject to such reasonable conditions (other than a condition requiring a monetary payment for the grant of the consent) as the highway authority may impose.

Any question whether such consent is or is not unreasonably withheld, or any conditions so imposed are or are not reasonable, shall be determined by arbitration.