168 



RAILROAD CURVES 



The following rule is sometimes applied in determining the 

 degree of curve: 



Rule. Measure the middle ordinate to a chord of 67.71 ft.: 

 express it in feet and decimals of a foot, and multiply by 10; the 

 result will be the degree of the curve. 



Other Ordinates. Any ordinate y to the curve at a distance 

 a from the middle point of a chord may be determined by means 

 of the formula: 



By using long chords, a curve may be laid out or obstacles 

 passed by means of ordinates. 



r' 



FIG. 8 





Suppose that it is required to run out the curve A EH, 

 Fig. 8, with several obstacles in the direct line of the curve, 

 as shown, Station 3 being the P. C., and the regular stations 

 on the curve being in the positions indicated by the numbers 

 4, 7, 8, etc. The positions of Stations 5 and 6 are indicated 



