Section 39H. Every contract entered into by or on behalf of the commonwealth for the construction, reconstruction or alteration of a public way shall contain a provision whereby the commonwealth agrees to indemnify the contractor against loss by reason of the liability to pay damages to others for entry upon any land included within the boundaries of the area within which the work is to be performed as set forth in the construction contract and the plans and specifications applying to such contract or any approved alteration thereof or for damage sustained upon any lands adjoining said land by reason of the flowage or drainage of water thereto or therefrom, in any case wherein such damages result from the failure of the commonwealth to take an interest or easement in such adjoining area, provided that the commonwealth acting by an authorized representative thereof, has issued a notice in writing to the contractor prior to the making of an entry upon such premises directing or permitting him to proceed with his contract and to make such entry upon the premises for the purpose of performing the work required by said contract, or any approved alteration thereof, and provided, further, that the contractor has given notice in writing to the contracting authority within fifteen days after receiving notice of any claim to come in and settle the same and upon the commencement of any action against him to come in and defend said action, but in no event shall any such damage claim be compromised or adjusted without the written consent of the commonwealth. The provisions of this section shall in no way relieve the contractor from any liability for damage to property of others caused by his negligence or that of his employees nor shall they be construed to require the commonwealth to indemnify the contractor against any loss resulting from such acts of negligence.