CAR TUNNEL’S 29 FANS

Greymouth Evening Star, 28 October 1932, Page 3

CAR TUNNEL’S 29 FANS

VENTILATION UNDER MERSEY. How is it possible to ventilate a tunnel through which motor vehicles can pass at the rate of 3.000 an hour, each journey occupying <Sj| minutes? The development of motor transport has brought with it a great many new problems, but none more striking perhaps than the one now beingtackled at Liverpool, where, at a cost of £7,000,000, a new tunnel has been driven below the River Mersey,, between Liverpool and Birkenhead, the longest under-water tunnel ip the world. Tho tunnel has been driven to a depth of 170 ft., and to withstand the enormous pressure it was essential to make a circular cutting so big that its internal diameter is 44ft. When the tunnel was started seven years ago less was known than now about the kind of ventilation requisite When heavy motor traffic is passing through.

Carbon monoxide, of course, was the great, enemy. Nobody at the outset knew exactly what proportions of carbon monoxide in the air were fatal, or what proportions could bo borne by •j human being without any deleterious

effects. Nor did anybody know exactly how much carbon monoxide was given off per hour by a motor-car or lorry. The result of experiments proved ’hat the best method of ventilation was to use the whole of the open, tunnel above the roadway as the exhaust duct. It is this system that is being installed. Six ventilating buildings are being built, three on each side of the river, and in these the blowing and exhaust fans are to be housed. .

Twenty-nine Mans are to be provided, but about half of them. are. for use only in emergency. Normally nine blowing fans and six exhausting fans will operate. It is confidently belieyed that the ventilation problem has been solved in the most satisfactory way, and that within twelve months the tunnel will be opened.