The New York Rapid-transit Subway

32 PARSONS ON NEW YORK RAPID-TRANSIT SUBWAY. [Minutes of directions, this junction is found in practice to be the limiting condition of the whole railway, and plans are now being prepared to add additional standing-tracks, so that in the event of two trains approaching simultaneously, one train may be allowed to proceed and the other passed to a standing-track so as to clear the main track for a closely-following train. Permanent Way. The specifications contemplated two types of track: in one the rail was to be laid on a continuous bearing of wooden blocks in the concrete floor, the grain of the wood to be transverse to the length of the rail, and the blocks to be held by a shoulder of concrete on the outside and by a removable steel angle on the inside ; the other was the standard American type of track consisting of wooden sleepers on stone ballast. The latter was adopted by tlie operating company. The sleepers are of yellow pine, not creosoted or otherwise chemically protected, and are 8 feet long, 8 inches wide, and 5 inches thick. Beneath the rail are steel tie-plates pressed into place by hydraulic pressure before being laid. The rail is of the Vignoles type, American Society of Civil Engineers section, weighing 100 lbs. per yard. This rail has a height and a width of base of 54 inches. Physical tests were imposed in the specifications and the following chemical composition was required—- Carbon.................................Not less than 0'55 per cent. „.............................more ,, 0'65 „,, Phosphorus ..........................» 2, » 0’085,, », Sulphur ....... » » » 0’07 „„ Silicon .............................„ less „ 0’1 „„ At the request of the company rails were laid in which the carbon ranged from 0'4 per cent, to 0’58 per cent., when the phosphorus exceeded 0’07 per cent. When the phosphorus was less than 0’07 per cent, the carbon was to range from 0-45 per cent, to 0’6 per cent. This mixture in practice was found to be too soft, and the higher percentage of carbon is being used. The rails are 33 feet long. Figs. 18 and 18a, Plate 6, show not only a cross section of the permanent way, but also the third rail carrying the current, its support on porcelain insulators, and its protective cover of wood. The maximum gradient is 1 in 33, or, facing stations where acceleration will be required, 1 in 60. With the alignment of the curves great care was taken. With one exception, referred to later, every curve having a radius less than 1,910 feet was laid out as a transition-curve by Crandall’s formula, which