Hill road alignment – first stage: While finalizing the alignment of a hill road, what is the first stage in the engineering process?

Introduction / Context:
Road alignment selection in hilly terrain is an iterative process. It balances earthwork, safety (grades, curves), environmental impacts, and cost. The process typically begins broadly and then narrows to precise details as data quality improves.

Given Data / Assumptions:

• We consider standard highway engineering workflow.
• Multiple candidate corridors must be screened.
• Field and map information together guide decisions.

Concept / Approach:
Reconnaissance is a rapid, low-cost, and wide-area appraisal used to identify feasible corridors. It comes before instrumented surveys. It relies on maps, satellite images, and field drives/walkovers to shortlist practical alignments that satisfy grade limits, minimize hairpin bends and landslide risk, and reduce tunneling/bridging needs.

Step-by-Step Solution:
Start with reconnaissance to scan large areas and reject infeasible corridors.Proceed to preliminary survey on shortlisted corridors for basic profiles and quantities.Undertake detailed survey on the preferred alignment for construction drawings and staking.Finalize trace-out on ground as the last pre-construction step.

Verification / Alternative check:
Most highway manuals and IRC guidance illustrate this exact sequence: reconnaissance → preliminary survey → detailed survey → setting out/trace-out.

Why Other Options Are Wrong:

• Preliminary/detailed survey and trace-out occur after reconnaissance.
• Desk study only is insufficient for terrain-driven decisions; a site view is critical.

Common Pitfalls:

• Selecting an alignment without early checks for landslides, unstable rock, or hydrology constraints.
• Underestimating costs of tunneling or deep cuttings that reconnaissance could flag.

Final Answer:
reconnaissance