Works (whenever constructed) to which this subsection applies shall not be treated as constituting an obstruction to the highway but as part of the highway, so that in particular—
the obligation of any person to maintain the highway, and
the obligation of any person having power to break open the highway to make good any damage or otherwise reinstate the highway,
extend to maintaining or, as the case may be, making good any damage to or otherwise reinstating the works.
Subsection (1) above applies—
to works of a description prescribed by regulations under section 90H above or specially authorised under section 90G above which conform to any requirements imposed by the regulations or authorisation, and
to works which fall within section 90GA above.