RAILROAD LOCATION 223 



the amount of timber available for construction, the amount 

 of rainfall, etc., should be carefully noted. In addition, the 

 engineer should note the probable quantities of excavation, 

 embankment, and bridging per mile; the prospective fuel 

 supply; the possibilities for business; and all other data 

 from which an approximate estimate of the cost of the proposed 

 railroad can be made. 



PRELIMINARY SURVEY 



The reconnaissance having been completed and a route 

 selected, the next thing is to make a preliminary survey. This 

 consists of an instrumental examination of the route for the 

 following purposes: (1) to determine the relative merits of 

 alternative 'routes that have been examined on the reconnais- 

 sance; (2) to obtain the necessary information for making 

 a map and a profile of the route; (3) to furnish data from 

 which to project the location; and (4) to determine, approxi- 

 mately, the amount of work to be done in the matter of clearing, 

 grading, and bridging, and to furnish data for an approximate 

 estimate of the cost of all materials and labor required for the 

 proposed road. 



Preliminary Estimate. In making a preliminary estimate, 

 great accuracy is not necessary, and no time should be wasted 

 in useless refinements of calculation. The estimate should be 

 high enough to cover all probable cost, and a liberal allowance 

 should be made to cover unforeseen contingencies that may 

 develop during construction. Most experienced engineers 

 make it a rule to add 10 % to a preliminary estimate in order 

 to provide for contingencies. 



In estimating for earthwork, the cross-sections may be con- 

 sidered as level cuttings; that is, the cross-section surface may 

 be considered as level unless its slope angle exceeds 10, in 

 which case a suitable allowance must be made for the slope. 

 The preliminary estimate, which also includes approximate 

 igures for material and labor required for culverts, bridges, 

 trestles, piers, and abutments is then classified and summarized. 

 A sample of a good form of a preliminary estimate of the cost 

 of a proposed railroad follows: 

 16 



