Accordingly, in order to remove these disabilities, a bold solution was elaborated in the form of a tunnel beneath the waterway connecting Sarnia on the Canadian with Port Huron on the United States side of the St. Clair River. It certainly was an audacious remedy for a perplexing problem. The river is 46 feet deep and is nearly half-a-mile wide, so that the tunnel had to be planned at a great depth. However, no better alternative could be offered, for a bridge was quite out of the question, so in 1886 the St. Clair Tunnel Company was formed as a subsidiary undertaking of the railway, to complete a subaqueous link of communication, with Mr. Joseph Hobson as chief engineer. As the topography of the land on either side is tolerably flat, the question of the approaches had to be settled, and a heavy grade at either end could not be avoided. Technical difficulties were encountered at the very start. A trial shaft was sunk on the Canadian side to a depth of 98 feet, while another shaft on the American side was carried down to 92 feet. The preliminary shafts were elliptical in shape, measuring 4 feet by 8 feet in diameters. When the requisite depths were obtained, galleries were driven at right angles beneath the river. These efforts proving satisfactory, it was decided to build the complete tunnel from either bank from shafts, as in the case of the Blackwall tunnel. The shafts were each 23 feet in diameter, and they were so built that there was a circular ring, the lower face of which carried a knife-edge digging into the ground. The soil was excavated from beneath this knife-edge, and as the brick-wall lining of the shaft was built upon the upper surface of the knife-ring, it was considered that the superimposed weight would drive the knife downwards as the earth beneath was removed. But these carefully-laid schemes and anticipations went astray. Exasperating failures and mishaps occurred, and at last the engineer changed his plans; the shaft method was abandoned. Instead, he decided to drive the tunnel from either end through the approaches. For this purpose the plant and machinery were removed inland from the shafts for a distance of 1,900 feet on the Canadian, and 1,800 feet on the American bank respectively. Two huge cuttings were driven downhill until the tunnel level was gained, when the burrow beneath the river was commenced. The tunnel itself consists of a circular iron tube or pipe of sufficient diameter to carry a single track. It is 19 feet 10 inches in diameter, is built up of cast-iron rings, and weighs complete 56,000,000 pounds, or about 25,450 tons. Boring was effected from either end by means of the hydraulic shield, and in less than three years the task was finished.