THE MERSEY TUNNEL

Taranaki Daily News, 8 September 1934, Page 13 (Supplement)

THE MERSEY TUNNEL

ARTERY OF TRADE

(By

O.E.W.)

The Mersey Tunnel, the largest underwater tunnel ever built, and one of the greatest engineering achievements of its kind in the world, was opened for traffic by the King on July 18. In., some degree it is the epitome of human ingenuity applied to meet the stress of a changing age. Fifty years ago the necessity of the work was realised by only the far-sight-ed; but in the last ten years motor transport has grown in dimensions so incredibly that the relief from congestion in the crowded areas of East Liverpool is already strongly apparent. The tunnel is designed for vehicular traffic carrying goods along the main highways of England and Wales to the great Atlantic port at the mouth of the Mersey. It gives access from Birkenhead to Liverpool proper by means of a subaqueous roadway in a gigantic “mine” scooped from the rock beneath the River Mersey. Its cost, over £7,000,000 —the incredible difficulties which its engineers faced and overcame, and the national interest which (characterised every stage of the venture are testimony eloquent of the “space-and-speed” problem which faces a modern world, centralised by the evolution of transport devices. The last decade has seen the civic corporations of the world’s great cities mortgage the revenue of a generation in engineering endeavours to solve the problem of traffic congestion. The ten millions spent on the Sydney harbour bridge and its approaches, the thirty millions spent in New York city in elevated roadways in the last eight yeans, bridges in London and San Francisco, underground railways, overhead railways, traffic deviations, by-passes, subways, and the hundred and one other ingenuities to meet the menace of stoppage in city arteries are measures and expenditures which the expert admits are only temporary in effect! Consideration of the history and wprk done in the Mersey tunnel as a “temporary measure” is indeed a stimulus for thought. The one permanently reproductive aspect of that tremendous work ,is the fact that, during the period of an acute trade depression which has hit the north of England harder, possibly, than any other part of the world, £8,000,000 has gone into the pockets of the people.. If there was no really pressing need for the Mersey Tunnel work before 1920, the ideal at least was no new one. George Stephenson in 1839 stated confidently that a tunnel beneath the river was a feasible idea, and in the years that followed several great engineers . endorsed that view, variously estimating ’ the cost of construction at between £250,000 and £10,000,000! .When, in 30 years, the tonnage handled by the Port of Liverpool increased from a little over one million to nearly twelve million tons annually, the problem was treated a little more seriously. Motor transport'at last rendered some anti-congestion measure imperative; and in 1925 so acute was the congestion in East Liverpool that over 90 per cent, of voting ratepayers in the Liverpool and Birkenhead areas approved the immediate beginning of the work. A statutory body known as the. Mersey Tunnel Joint Committee was formed, and the Mersey Tunnel Act passed both Houses in the same.- year. On December 15 Princess Mary turned on the compressed air used in the drills to sink the first shaft. At that date the estimated cost of the work was £5,000,000. Time and incredible difficulties added nearly £3,000,000 to the total. The resumption of property and demolition work involved in preparing the approaches was, as in the case of the Sydney bridge, tremendous; It was not until the greater portion of this work had been done that in 1929 it was realised, by observation in the first section of the tunnel itself, that ,an elaborate air-ventilation system would have to be installed, and that the seepage of water from the bed of the river would have to be dealt with uptil the concrete sealing was completed. Two years later an upwards, half-transverse’ ventilation system was adopted to overcome the carbon-monoxide menace, and the air was syphoned through the shafts by means of gigantic fans, electrically driven. All this additional work was necessary quite apart from the completion of the main drive—a 44 foot bore, graded to the centre at one in 30, concrete sealed, floodlit by electricity, macadamised for four lines of traffic at the base, drained, and shelled with cast iron. The immensity of the undertaking is shown by the official job statistics.. One and a quarter million tons of rock were quarried in the main tunnel, requiring the use of half a million pounds of explosive. Over a quarter .of a milliop tons of concrete was used ,in the sealing and road formation, and 82,000 tons of cast iron comprised the sheathing. From June, 1926, to August, 1931, one ton of spoil came from the . workings every two minutes, for 24 hours a day. . How strenuously the muddy Mersey resisted the breaking down of its ageold barrier is shown by the estimate that for every ton of rock excavated 26 tons of seepage water had to be pumped a height of 200 feet. The shell of rock protecting the tunnel itself from the seepage on the bed of the river is only a little more than 30 feet thick, so that the structure must have tremendous resilence against the eroding action of water and increasing pressure. The airshaft system, capable of delivering two and a half million cubic feet of fresh air every minute, provided a mechanical problem only slightly less .complicated and immense. That • provision added nearly two-fifths to the total, cost of the undertaking, despite the fact that the use of expensive machinery and conveniences was duplicated. And for what reason, in practical • effect, was this miracle of labourorganisation and applied science performed ? Merely to provide a fraction under three miles of roadway between thickly populated areas in a seaport that is, or was, divided by a river! The deviation of traffic from the congested areas of East Liverpool, the forging of a direct link between the Liverpool waterside and the southern highways—in other words, the saving of half an hour of time for the countless thousands of motor vehicles passing daily to and from the berths of trans-Atlantic cargo and passenger steamers—is calculated by one statistician to save commerce the price of the entire job in the course of one year!

Perhaps more forcibly than any other engineering feat of the century, the Mersey Tunnel gives point and. focus to the tremendous access difficulties which a mechanised high-speed age has created in its wake. The fact that experts have admitted such a stupendous business relieves temporarily, rather than permanently, the congestion' in the main seaport of manufacturing England, makes one wonder what immensities in human undertaking will be forced upon the future by aS urgent a necessity as that which impelled construction of the present tunnel.