Construction and Engineering Surveying
Domain 6 tests the field procedures that transfer design to the ground: elevation control, cut-and-fill staking, slope staking, machine control, and as-built verification against project tolerances.
Elevation control
- Differential leveling: HI = BM elevation + backsight; ground elevation = HI − foresight. Turning points must be stable and readings balanced.
- Trig levels from a total station need curvature and refraction handled on long shots; short construction shots generally do not.
- Close levels on a second benchmark. A single-benchmark loop proves nothing about datum error.
Stakeout
- Offset stakes with cut/fill written to hundredths; hub and tack for horizontal position; guard stakes for grading.
- Slope staking locates the catch point where the design side slope meets original ground.
- Machine control and rover stakeout still depend on a correct site calibration and a checked control network.
Iowa DOT work
Projects follow the Iowa DOT Standard Specifications: item-based pay quantities, specified tolerances, and survey records supporting measurement and payment. As-builts must show what was built, not what was designed.
Worked example
Benchmark elevation 100.00 ft, backsight 4.32 ft, so HI = 104.32 ft. Station 12+00 foresight 3.15 ft → existing ground = 104.32 − 3.15 = 101.17 ft. Design grade 102.00 ft → 102.00 − 101.17 = 0.83 ft cut. Station 14+00 foresight 3.50 ft → ground = 100.82 ft; 102.00 − 100.82 = 1.18 ft fill. Sign convention: positive cut, negative fill - write it on the stake so the operator cannot reverse it.
Traps
Reversed cut/fill signs; forgetting to reset HI after a turning point; rod on soft or frozen ground; mixing assumed datum with NAVD88; staking from an unadjusted calibration; as-builts copied from design files; no second benchmark check.