TRACK WORK 



239 



In curving rails, the ordinate is measured by stretching 

 cord from end to end of the rail against the gauge side, 



shown in the accompanying illustration. Suppose the rail 

 AB is 30 ft. in length, and the curve 8, then the middle 

 ordinate at a should be 



302 



m = = .157 ft. = 12 in. 



8X716.78 



To insure a uniform curve to the rails, the ordinates at the 

 quarter points b and b f should be tested. In all cases the quarter 

 ordinates should be three-quarters of the middle ordinate. In 

 the illustration, if the rail has been properly curved, the quarter 

 ordinates at b and b' will be f X 1 1 in. = U, say If. 



MIDDLE ORDINATES, IN INCHES, FOR CURVING RAILS 



Length of Rail, in Feet 



17 



