Limiting ground gradient for locating a triangulation baseline on even slopes For practical baseline layout in geodetic/survey work on evenly sloping terrain, which limiting gradient is generally recommended so that reductions to horizontal and measurement corrections remain manageable?

Introduction / Context:
A triangulation baseline should be measured with the highest possible precision because it controls the scale of an entire triangulation network. On sloping ground, choosing an alignment with a mild gradient helps reduce systematic errors and simplifies reductions to the horizontal.

Given Data / Assumptions:

• The ground is evenly sloping; alignment choice is flexible within a corridor.
• Instruments and tape/EDM measurements require corrections for slope, temperature, and tension.
• Good practice targets small slope corrections to minimize uncertainty.

Concept / Approach:
When selecting or setting out a baseline, surveyors prefer gentle grades to minimize the magnitude of the slope correction and to simplify staging of tripods or invar tapes. A commonly cited limiting gradient is about 1 in 12, which balances practical site constraints with the need for precision.

Step-by-Step Solution:
Evaluate candidate gradients in terms of slope correction magnitude and setup stability.Milder gradients (1:12) produce smaller vertical components and smaller correction terms than steeper choices (1:8, 1:6).Thus, 1 in 12 is generally recommended as a limiting value on evenly sloping ground.

Verification / Alternative check:
Historic triangulation manuals emphasize gentle grades or use of stepped supports to approximate horizontal measurements; values near 1:12 recur as practical limits in many references.

Why Other Options Are Wrong:

• (b), (c), (d) are progressively steeper, increasing corrections, instrument levelling difficulty, and setup time.
• (e) is inapplicable because a standard guidance exists.

Common Pitfalls:
Assuming any slope can be handled equally by EDM: while EDM can reduce some burdens, control of instrument geometry and atmospheric corrections still benefits from gentler alignments.

Final Answer:
1 in 12