law: 436. Prohibition of obstruction or molestation in execution of work.
  No person shall obstract or molest any person authorised or empowered by or under this Act or any person with whom the Corporation or any of the municipal authorities specified in section 44 has lawfully contracted, in the execution of his duty or of anything which he is authorised or empowered or required to do by virtue or inconsequence of any of the provisions of this Act or any bye-law made thereunder, or in fulfilment of his contract, as the case may be.