170 



RAILROAD CURVES 



FIELD NOTES FOR CURVES 



Various styles of field notebooks are published, in which the 

 pages are ruled to suit the different kinds and methods of field 

 work. The following, which are the field notes of a portion of a 

 line containing a curve, represent a good form for recording 

 the field notes of a curve that is run in by the method of zero 

 tangent. 



In the first column are recorded the station numbers; in the 

 second column, the deflections with the abbreviations P.C. and 

 P. T., together with the degree of curve and the abbreviation 

 R or L, according as the line curves to the right or left. At 

 each transit point on the curve, the total or central angle from 

 the P. C. to that point is calculated and recorded in the 

 third column. This total angle is double the deflection angle 

 between the P. C. and the transit point. In the accompanying 

 notes, there is but one intermediate transit point between the 



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P. C. and the P. T. The deflection from the P. C. at Station 

 3+20 to the intermediate transit point at Station 4+50 is 

 2 36'. The total angle is double this deflection, or 5 12', 

 which is recorded on the same line in the third column. The 

 record of total angles at once indicates the stations at which 

 transit points are placed. The total angle at the P. T. will be 

 the same as the angle of intersection, provided the work is 



