945 CMR 4.00 applies to the Commonwealth and any of its public agencies or authorities when procuring the construction, repair or rehabilitation of a publicly-owned highway, railway, bridge, tunnel, building platform or any component thereof and for which the certified estimate of cost exceeds $50,000,000, or when entering into a contract or lease to procure, directly or indirectly, the construction, repair or rehabilitation of a privately-owned, publicly-used highway, railway, bridge, tunnel, building platform or any component thereof and for which the Certified Estimate of Cost exceeds $50,000,000.