RAILROAD CURVES 



TABLE (Concluded) 

 a = 100'. 1 in 10 ft. 



189 



CT = C'T. Run the two tangents to their point of intersec- 

 tion T, measure back from T the distances TC and TC', and 

 at C and C set stakes marked P. Si. 



Set up the transit at P. Si, sight on T, and then set stakes 

 on the spiral exactly as on a simple circular curve, except that 

 the deflection angle for each stake is computed by the formula 

 or taken from the tables. When the stake at A (marked P. 82) 

 has been set, move the transit to A, backsight on P. Si, and 

 deflect from this direction the angle necessary to bring the 

 telescope tangent to the simple circular curve at A. This 

 angle is equal to the angle of deviation A minus the angle of 

 deflection VCA . Run in the circular curve as usual. 



When the stake at B (marked P. 82') has been set, move 

 the transit to C', backsight on T, and stake out the second 

 spiral in exactly the same manner as the first, using the deflec- 

 tion angles computed for the first spiral. When the last stake 

 along C' B has been set, backsight on T, and continue the 

 survey along the tangent C'R'. 



