. Electric railway journal . forgotten. Mr. Harte was assured by Mr. Clark that there will beno greater trouble in laying out this system of spiralsfrom the manufacturers drawings than has been thecase with any other system. L. C. Datz explained thatmost of the field work is done by getting the point ofintersection of the two tangents, bisecting it and gettingthe middle of the curve. The steel companies can easilyfigure out two or three more points to assist in the fieldwork of laying out the curve. To these explanations,Mr. Harte replied that with this information the fieldman is all right, b
. Electric railway journal . forgotten. Mr. Harte was assured by Mr. Clark that there will beno greater trouble in laying out this system of spiralsfrom the manufacturers drawings than has been thecase with any other system. L. C. Datz explained thatmost of the field work is done by getting the point ofintersection of the two tangents, bisecting it and gettingthe middle of the curve. The steel companies can easilyfigure out two or three more points to assist in the fieldwork of laying out the curve. To these explanations,Mr. Harte replied that with this information the fieldman is all right, but in many instances the informationis not at hand when wanted. With every one of thesespirals it is a more or less complicated proposition todetermine points not given by the standard chord butsome require much more complicated calculations thanothers. This point should be carefully considered beforea decision is reached. In reference to the question of Mr. Harte, C. said that the proposed spirals are simple com-. FIG. 3—COMPARISON OP PROPOSED UNIFORM SPIRALSNote—Spiral number equals length of arcs of that spiral in feet and tenths. Figures below arcs give to nearest foot radii of inner gage lines. Likewise in subway and in extensive surface changes inlarger cities, it is often essential to know clearancepoints at odd intervals to determine on the one handwhether existing posts, manholes or similar objects willhave to be shifted, or on the other hand to fix locationsof such objects. Under these conditions, will the pro-posed standard be a help or a hindrance? The proper step is to choose that spiral which willwork best considered from all angles. As it will benecessary for the manufacturers to make a change at thetime of the adoption of any standard spiral, they are theleast concerned with the mathematical end of it, as thecalculations for them when once made are complete. Theman who works in the field and finds himself confrontedwith the necessity of determining
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