. The Street railway journal . ubstantial manner. The suburban lines of the LongIsland Railroad form several loops or meshes of a net workwhich may afford an opportunhy for the construction of addi-tional transmission lines by other routes, should future con-ditions require such a development. The trunk line is designed to carry eight three-phase trans-missions circuits, consisting of three 250,000-circ. mil cableseach, together with eight low-tension cables of 500,000 each. As the latter, when installed must be 25 ft. above theground, and as there must be a reasonable clear space be
. The Street railway journal . ubstantial manner. The suburban lines of the LongIsland Railroad form several loops or meshes of a net workwhich may afford an opportunhy for the construction of addi-tional transmission lines by other routes, should future con-ditions require such a development. The trunk line is designed to carry eight three-phase trans-missions circuits, consisting of three 250,000-circ. mil cableseach, together with eight low-tension cables of 500,000 each. As the latter, when installed must be 25 ft. above theground, and as there must be a reasonable clear space betweenthe low-tension and high-tension circuits, no argument is re-quired to demonstrate the necessity for using steel-tower con-struction to carry such an unusual weight of overhead con-ductors. The branch line transmission circuits, however, are notintended to carry more than two three-phase transmission cir-cuits and four low-tension cables on a single line of condition enabled the use of wooden poles, of which an. FIG. 10.—WOOD POLE CONSTRUCTION, LOOKING NORTHFROM JAMAICA BAY extra heavy type was selected in order that the idea of stabil-ity might be consistently carried out. STEEL POLES The Steel poles are of various sizes to meet different condi-tions. They are all designed to carry twenty-four_ 250,000-circ. mil cables, on their upper portions, and underneath theman additional load of eight 500,000-circ. mil low-tension cableswhich local regulations require to be at least 25 ft. above theground. The spans between steel poles average 150 ft. inlength, except where turning corners or carrying the cablesover railroad tracks. The poles when fully loaded as above,are able to carry safely a weight of 4500 lbs. of cable. The steel poles are built of four corner angles, connected together by angles and plates forming a lattice type of con-struction. They are tapered uniformly to the top on twosides and to within about 73/^ ft. of the top on the other twosides, the ta
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectstreetr, bookyear1884
