To achieve 2nd Order accuracy, what is the required vertical accuracy specification for 1 km of double-run leveling without a micrometer?

• A. 0.2 mm
• B. 1.5 mm
• C. 2.0 mm
• D. 0.8 mm

Answer: (D)

Vertical accuracy in leveling is about how close the measured elevation changes must be to the true values, expressed as a tolerance per unit distance. For second-order accuracy using double-run leveling without a micrometer, the standard allowance is 0.8 millimeters per kilometer. That means over a 1 km stretch, the vertical error should stay within 0.8 mm. The other tolerances are either tighter or looser than what second-order double-run leveling without a micrometer requires, so 0.8 mm per kilometer is the correct specification.