TUBE RAILWAYS OF NEW YORK.

New Zealand Herald, Volume L, Issue 15298, 10 May 1913, Page 5 (Supplement)

TUBE RAILWAYS OF NEW YORK.

Foil its wonderful system of underground railways New York has to. thank Mr. W. G. McAdoo, who has recently been offered by President Wilson, and has accepted, the Treasury forolio. A most interesting account of these lines, now 133 miles in length and shortly to be increased to 228 miles, was given recently at a meeting of - the Institution of Civil. Engineers by Mr. . G. Duncan Snyder, M.I. C.E. The lecturer recalled the fact that practically all New York's "underground! railways, were of the shallow type. A track line on. Lexington Avenue was being constructed, with local tracks •near the surface and express trains tunnelled at a deep level. The latter caused less inconvenience during : construction, - but were more expensive to work •'on account of the necessity for lifts. ■ ' Construction and Cost. In a typical section of the shallow underground line the internal height varied from 13ft 2in to. 15ft 4in, and the width for a single track was lift 6in to 13ft 2in. The construction for shallow subways, as the lines are , called, was either of - steel beams in the roof and sides, embedded in . concrete, or of reinforced concrete. The work .of construction was proceeded with under a . temporary wooden flooring, which carried the traffic. The depth of the subways in certain parts necessitated the underpinning of adjoining foundations and j the temporary support of the elevated rail- | way. The subway lining was of concrete ' excepting, the iron-lined . subaqueous tunnels. In the case of rock tunnels these were driven with a top heading, though a portion of the Brooklyn subway ; was excavated with a steam shovel. The subaqueous tunnels were usually driven with shields and compressed air, and were lined with._cast-iron. The cost of the earth excavations in New York was 9s to £1 5s per cubic yard, rock excavation costing 16a to £2 8s; tunneling £1 13s to £1 18s, and concrete £1 12s to £2 4s - per cubic yard. Owing to the very varied strata through which the subways were cut, the cost of these lines was diverse, ranging from £167,000 to £800,000 per mile of track, as compared with £40,000 to £120,000 , per mile in the case of the construction of elevated, lines, but excluding equipment in both cases. .

The Underground Track. The cars used', Mr- Snyder said, were of steel, and there was a tendency to increase their size, the most recent being ,70ft. long,'. 9ft 6in wide, and 12ft 6in high, the weight being from forty to fifty tons, approximately. The permanent way consisted of crushed stone on which wooden sleepers were laid carrying "T" rails. Maximum gradients ranged from 1 in 33 to 1 in 12.5, and the minimum radii ofcurves from 90ft to 150 ft. Four-track lines were worked with express trains on one pair of tracks and local trains on the other pair. As regards signalling, automatic block signals were not used on the older elevated lines nor on the local tracks of the • New York subways except at special points, but they were used on the express tracks. A headway ,of 90sec. could be with automatic , block signals with a speed of forty miles per hour, and a headway ; of 20sec. had been maintained without signals and with low speed. Traffic v Density. The popularity of the lines was made clear from the lecturer's statement, that the number of passengers per annum was increasing as the square of the population* New York had 43 passengers per head of population in 1860 and 322 in 1910, and if the present rate were maintained in the future the number would be. 913 in 1950. Throughout the whole of . the underground system there was a uniform fare of 5 cents for any distance, an arbitrary rate appreciated, doubtless, by the public, but causing " much dissatisfaction among managers." The density of traffic on the New York subway was 4,000,000 passengers per mile of track per annum. The peak .load on most lines was between five. p.m. and six p.m., and amounted to about 75 per cent, of the total for the d!ay. About 7 per cent, of. the annual traffic was. carried in the month of July, and about 9 per cent, ,in December. To accommodate the growing . traffic < trains had been in-: creased in length and > from three cars 'to ten cars, and still longer trains were proposed. . : y- ' ____