PROCEEDINGS 



OF THE 



Delaware County Institute of Science 



Vol.. VI, No. 4 July, 191 i 



THE TRANSITION CURVE. 



BY C. M. BROOM ALL. 



Of the various factors making for rapidity and safety of 

 railway travel, the fundamental one is, of course, the track. 

 The best mechanical construction in this regard is essential, 

 and yet even with everything mechanically perfect the system 

 remains far from satisfactory for high speed travel unless 

 certain further conditions are complied with. There is still 

 something lacking, namely, that certain group of refinements 

 which may~be classed under the term alignment. Alignment 

 consists of perfect straightness of straight track, of easy curv- 

 ature of curved track, of proper superelevation on curves, of 

 the transition curve, etc. In short, alignment concerns the 

 geometry of the track in contradistinction to its mere mecha- 

 nical construction. Without this final touch of geometrical 

 perfection comfort and safety in fast travel are impossible. 



The railroad line in its simplest conception consists essen- 

 tially of a series of straight stretches or tangents uniting a 

 series of simple circular arcs. In this simple conception of 

 the track one grave difficulty presents itself, and that is the 

 impossibility of the train passing from the straight to the 

 curved track, and vice versa, without dangerous or unpleasant 

 shock. On curves it is necessary that the outer rail be ele- 

 vated above the inner in order that the dangerous pressure 

 due to centrifugal force against the outer rail may be 

 offset by the attraction of gravitation tending to make the 



