TUBE RAILWAYS OF NEW YORK.

Star (Christchurch), Issue 10768, 14 May 1913, Page 4

TUBE RAILWAYS OF NEW YORK.

For its wonderful system of underground railways New York has to thank Mr W. G. M'Adoo, who has recently been offered by President Wilson, and has accepted, the Treasury portfolio. A most interesting account of these lines, now 133 miles in length, and shortly to bo increased to 223 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 four-track lino on Lexington Avenue was being constructed, with local tracks near the surface and express trams 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.

In a typical section of the. shallow underground line the internal height varied, from 13ft 2in to loft 4in, and the Avidth for a single track Avas lift 6in to 13ft 2in. The construction for shallow subways, as the linos aro called, was either of steel beams in the root' and sides, embedded in concrete, or of reinforced concrete. The aawß of construction was proceeded with under a temporary Avoodeu flooring, which carried the traffic. The depth of the subways in certain parts necessitated theunderpinning of adjoining foundations and the temporary support of the elevated railway. The subAvay lining was of concrete excepting the iron-lined subaqueous tunnels. In the case of rock tunnels theses were driven Avith a top heading, though a portion of the Brooklyn subway was excavated with a steam shovel. The subaqueous tunnels Aver usually driven witli shields and compressed air, and Avero lined Avith cast-iron. The cost of the earth excavations in New York Avas 9s to £1 5s per cubic yard, rock excavation costing 16s to £2 Ss; tunnelling £1 13s to £1 18s, and concrete £1 12s to £2 4s per cubic yard. Owing to the very varied strata'thrcugh Avhich the subways Avere cut. the cost of these lines Avas diverse, ranging from £167,000 to £BOO.OOO per mile of track, as compared Avith £40,000 to £120,000 per mile in the case of the construction of elevated lines, hut excluding equipment in both cases. The cars used, Mr Snyder said, were of steel, and there was'a tendency to increase then; size, the most recent, being 70ft long, oft fiin wide and 12ft Gin high, the weigiit being from forty to fifty tons approximately. The permanent Avay 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 of curves 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 Avere used on the express tracks. A head•Avay of OOsec could be maintained with automatic block signals Avith a speed of forty miles per hour, and a headAvay of 20see had been maintained Avithout signals and with low speed. The popularity of the lines Avas made clear from the lecturer's statement, that the number of passengers per annum was increasing as the squire of the population. Xew York had 43 passengers ne-r head of population in 1800 and 322 in 1910, and if the present rate were maintained in the future the number would be 913 in 1950. Throughout the Avhole of the underground system there was a uniform fare of •"> cents for any distance, an arbitrary rate appreciated, doubtless, by the public, but causing "much dissatisfaction among managers." The density of traffic on the Xew York subway was 4,000.000 passengers per mile of track per annum. The p<*ak load on most, lines was between o p.m. and and R p.m., and amounted to about 7o per cent of the total for tho day. About 7 per cent, of the annual traffic Avas car. rird in the month of July, and about 9 per cent in December. To accommodate the growing traffic trains had lii-en ii;cr(-;ir-<-d in length and from litres' r.ii- i-o ten e,ns. and still lunger l]':;ii.--i .I'Mc i>n>|ji><':d.