SECTION 1.  Section 29C of chapter 149 of the General Laws as appearing in the 2008 Official Edition is hereby amended by striking out such section in its entirety and inserting in place thereof the following new section 29C:—

            Section 29C. Any provision for or in connection with a contract or subcontract for construction, reconstruction, installation, alteration, remodeling, repair, demolition or maintenance work, including without limitation, excavation, backfilling or grading, on any building or structure, whether underground or above ground, or on any real property, including without limitation any road, bridge, tunnel, sewer, water or other utility line, which requires one party to indemnify or insure the other party, or anyone identified in the contract or subcontract as an indemnitee or additional insured, for injury to persons or damage to property to a greater extent than the proportion of said injury or damage proximately caused by the negligence of the indemnitor  shall be unenforceable and void. Any such indemnification or insurance provision shall be interpreted to require indemnification or insurance only to the proportional extent the negligence of the indemnitor, its agents or employees is a proximate cause of the injury or damage.

            Nothing in this section shall be construed to alter existing law governing the liability

of joint tortfeasors to a plaintiff.