(d)to construct, form or lay out any works, upon land lying nearer to the middle of a highway than a distance equal to one-half of its standard width prescribed under Section 11, or upon land lying between the boundary of a highway and the building line determined in respect of the highway under Section 12 ; provided, however, the these restrictions shall not apply to any works necessary for the repair, renewal, enlargement or maintenance of any sewer, drain, electric line pipe, duct or other apparatus, constructed in or upon the land before the date on which the restrictions came into force or with the consent of the highway authority, on or after that date.