When a street, alley, public highway, sidewalk, wharf, or landing within a municipal corporation is graded, or pavements are constructed in conformity to grades established by the authorities of the municipal corporation, and the expense of such work is assessed on the lots or lands benefited thereby, such lots or lands shall not be subject to any special assessment occasioned by any subsequent change of grade in such pavement, sidewalk, street, alley, public highway, wharf, or landing unless a petition for the change is subscribed by a majority of such owners. The expense of improvements occasioned by such change of grade, not so petitioned for, shall be included as part of the cost of the improvement to be paid by the municipal corporation.