About the year 1765 an Act was passed empowering a turnpike-road to be constructed between Harrogate and Boroughbridge. The business of contractor had not yet come into existence, nor was the art of road-making much understood; and in a remote country place such as Knaresborough the surveyor had some difficulty in finding persons capable of executing the necessary work. The shrewd Metcalf discerned in the proposed enterprise the first of a series of public roads of a similar kind throughout the northern counties, for none knew better than he did how great was the need of them. He determined, therefore, to enter upon this new line of business, and offered to Mr. Ostler, the master surveyor, to construct three miles of the proposed road between Minskip and Fearnsby. Ostler knew the man well, and having the greatest confidence in his abilities, he let him the contract. Metcalf sold his stage-waggons and his interest in the carrying business between York and Knaresborough, and at once proceeded with his new undertaking. The materials for metaling the road were to be obtained from one gravel-pit for the whole length, and he made his arrangements on a large scale accordingly, hauling out the ballast with unusual expedition and economy, at the same time proceeding with the formation of the road at all points; by which means he was enabled the first to complete his contract, to the entire satisfaction of the surveyor and trustees. This was only the first of a vast number of similar projects on which Metcalf was afterwards engaged, extending over a period of more than thirty years. By the time that he had finished the road, the building of a bridge at Boroughbridge was advertised, and Metcalf sent in his tender with many others. At the same time he frankly stated that, though he wished to undertake the work, he had not before executed anything of the kind. His tender being on the whole the most favourable, the trustees sent for Metcalf, and on his appearing before them, they asked him what he knew of a bridge. He replied that he could readily describe his plan of the one they proposed to build, if they would be good enough to write down his figures. The span of the arch, 18 feet," said he, "being a semicircle, makes 27: the arch-stones must be a foot deep, which, if multiplied by 27, will be 486; and the basis will be 72 feet more. This for the arch; but it will require good backing, for which purpose there are proper stones in the old Roman wall at Aldborough, which may be used for the purpose, if you please to give directions to that effect." It is doubtful whether the trustees were able to follow his rapid calculations; but they were so much struck by his readiness and apparently complete knowledge of the work he proposed to execute, that they gave him the contract to build the bridge; and he completed it within the stipulated time in a satisfactory and workmanlike manner.