Mass. Gen. Laws ch. 82 § 16
When a highway which has been laid out, specifically repaired, relocated or altered, is completed, in whole or in part, the commissioners shall view and carefully examine it throughout, and if they find that it has been well made according to their directions, they shall order the proportion of the expense for which the county is liable under section twelve or which has been assessed upon the land benefited to be paid by the county. Said commissioners, before work ordered by them is wholly completed, may pay to the city or town such proportion of the county's share of the expense as they determine, having regard to the amount of work done and the proportion of the expense which they have determined the county shall pay.
Mass. Gen. Laws ch. 82, § 16