Whenever the county commissioners have heretofore assisted or shall hereafter assist any municipality in the building of the whole or any portion of a bridge and it shall afterwards appear to the commissioners that the care, maintenance and responsibility of said bridge is greater than it is reasonable that the said municipality should bear, they may enter such bridge upon record as a county bridge, and it shall thereafter be a county bridge the same as if it had originally been so entered on record.
16 P.S. § 5757