Although the works of the Liverpool and Manchester Railway are of a much less formidable character than those
of many lines that have since been constructed, they were then regarded as of the most stupendous description. In deed, the like of them had not before been executed in England. It had been our engineer’s original intention carry the railway from the north end of Liverpool, round the red-sandstone ridge on which the upper part of the town is built, and also round the higher rise of the coal formation at Rainhill, by following the natural levels. But the opposition of the landowners having forced the line more to the south, it was rendered necessary to cut through the hills, and go over the high grounds instead of round them. The first consequence of this alteration in the plans was the necessity for constructing a tunnel under the town of Liverpool 1½ mile in length; the second, a long and deep cutting through the red-sandstone rock at Olive Mount; and the third and most serious of all, was the necessity for surmounting the Whiston and Sutton hills by inclined planes of 1 in 96. The line was also, by the same forced deviation, prevented passing through the Lancashire coal-field, and the engineer was compelled to carry it across the Sankey valley, at a point where the waters of the brook had dug out an excessively deep channel through the marl-beds of the district.
The principal difficulty was experienced in pushing on the works connected with the formation of the tunnel under Liverpool, 2200 yards in length. The blasting and hewing of the rock were vigorously carried on night and day; and the engineer’s practical experience in the collieries here proved of great use to him. Many obstacles had to be encountered and overcome in the formation of the tunnel, the rock varying in hardness and texture at different parts. In some places the miners were deluged by water, which surged from the soft blue shale found at the lowest level of the tunnel. In other places, beds of wet sand were cut through; and there careful propping and pinning were necessary to prevent the roof from tumbling in, until the masonry to support it could be erected. On one occasion,
while the engineer was absent from Liverpool, a mass of loose moss-earth and sand fell from the roof, which had been insufficiently propped. The miners withdrew from the work; and on Stephenson’s return, he found them in a refractory state, refusing to re-enter the tunnel. He induced them, however, by his example, to return to their labours; and when the roof had been secured, the work went on again as before. When there was danger, he was
always ready to share it with the men; and gathering confidence from his fearlessness, they proceeded vigorously with the undertaking, boring and mining their way towards the light.
The Olive Mount cutting was the first extensive stone cutting executed on any railway, and to this day it is one of the most formidable. It is about two miles long, and in some parts 80 feet deep. It is a narrow ravine or defile cut out of the solid rock; and not less than 480,000 cubic yards of stone were removed from it. Mr. Vignolles, afterwards describing it, said it looked as if it had been dug out by giants.
The crossing of so many roads and streams involved the necessity for constructing an unusual number of bridges. There were not fewer than 63, under or over the railway, on the 30 miles between Liverpool and Manchester. Up to this time, bridges had been applied generally to high roads where inclined approaches were of comparatively small importance, and in determining the rise of his arch the engineer selected any headway he thought proper. Every consideration was indeed made subsidiary to constructing the bridge itself, and the completion of one large structure of this sort was regarded as an epoch in engineering history. Yet here, in the course of a few years, no fewer than 63 bridges were constructed on one line of railway! Mr. Stephenson early found that the ordinary arch was inapplicable in certain cases, where the headway was limited, and yet the level of the railway must be preserved. In such cases he employed simple cast-iron beams, by which he safely bridged gaps of moderate width, economizing headway, and introducing the use of a new material of the greatest possible value to the railway engineer. The bridges of masonry upon the line were of many kinds; several of them askew bridges, and others, such as those at Newton and over the Irwell at Manchester, straight and of considerable dimensions; but the principal piece of masonry was the Sankey viaduct.
