Modern surveys, though still requiring field-work, albeit with smaller survey parties,1 have benefitted from new technologies. Along with existing large-scale topographic maps “... precision cameras, air photographs, electronic distant measurers, first-order plotting instruments and ... computers”2 together with mechanized trail clearing,3 have all contributed to the accuracy and ease of the surveying process. However, historically, the establishing of a suitable route required the following surveys.4
The exploratory or reconnaissance survey was a rapid, yet careful, study of the area under consideration. Surveyors had to understand the nature of the country and be able to assess its economic potential. All possible routes had to be examined with construction and operational costs of a projected railway borne in mind. Gradient, curvature, the necessity for cuts and fills, bridging and tunneling, all had to be considered; matters only an experienced surveyor could judge. Distances were usually paced, directions obtained by prismatic compass, and heights determined by aneroid barometers. A generalized map could then be compiled on the basis of the data collected.
This was an instrumental survey of each route selected for more careful study. Trial lines would be run to obtain “precise measurements of distances, directions, and altitudes,”5 using the engineer’s chain (100 feet), the transit-theodolite, and the spirit level, respectively. On either side of the survey line information on the topography and soil would be collected. Slope data, for contouring, would be determined by the use of a clinometer, though in some circumstances the transit and stadia or plane table and alidade would be used. Stakes every 100 or 200 feet would be driven into the ground indicating the route. Bench marks would also be indicated at determined intervals.6 The resulting plani-metric map would show the tangents (straight lines) and be accompanied by profiles enabling the engineers to assess the need for cuts and fills and the costs thereby entailed.
A typical survey party would be made up of, Chief surveyor, Transitman (probably second in command), Leveller, Rodmen, Chainmen, Topographer, Draughtsman, Axemen (if required), a Cook and Packers.
Having studied the alternative routes obtained by the preliminary surveys the most suitable and cost-effective one was chosen, though political expediency might have a bearing on the final decision. In this paper-ground survey curves would be derived from the tangent data, plotted and staked. The survey would be refined by additional ground work and all necessary corrections, adjustments and improvements made. The resultant detailed line would then be thoroughly staked ready for the construction gangs to follow.
During construction of the railway line resident engineers would be located at intervals along the right-of-way. Besides making sure that any discrepancies in the location survey had been corrected, further improvements in the alignment made, if required, and all the guide stakes kept in place, the engineers made sure that all specifications and plans were adhered to and all contractual obligations observed.