Topographic Mapping and Construction Surveying
This domain tests whether you can turn field measurements into usable terrain and layout information: contour interpretation, mapping accuracy standards, quantity computation, and construction stakeout procedure.
Topographic mapping
Contour interval sets the map's vertical resolution; index contours are heavier and labeled. A contour crossing a stream forms a V pointing upstream. Breaklines control contours at grade changes and embankments - a DEM without them will smear a ditch into a smooth slope. Positional accuracy is stated as a standard such as the ASPRS accuracy classes, and LiDAR vertical accuracy is reported as RMSEz; check the project specification before promising a number.
Construction layout
Establish horizontal and vertical control on the project datum (typically NAVD88), then set offset stakes, slope stakes, and grade ("blue top") stakes with the cut or fill written on the lath. Machine control and RTK layout still require a verified site calibration and periodic check shots on independent control. As-built surveys close the loop. In Missouri, notify Missouri One Call (811) before excavation and honor the statutory waiting period - typically three working days.
Worked example
Earthwork between two cross sections 100 ft apart with areas of 240 sf and 360 sf. Average end area volume = ((240 + 360)/2) × 100 = 30,000 cf. Divide by 27 to get 1,111 cy. Apply a shrinkage factor if the material is compacted fill; note that the prismoidal formula would give a slightly smaller value for the same three sections.
Traps
Working in grid distances on a ground layout; computing volumes in cubic feet and reporting cubic yards; forgetting shrinkage or bulking; staking from an unchecked benchmark; and letting grade stakes be reset by site personnel without survey verification.