Reconnaissance for highway alignment – recording grade line with 2 m poles In the final stage of reconnaissance, when grade-line details are noted on 2 m poles, what information do these notations communicate in the field?

Introduction / Context:Reconnaissance is the early stage of route selection for highways. Before detailed survey, designers mark grade-line cues along the candidate corridor. Simple, visible field indicators such as 2 m poles and pegs help communicate alignment, spacing, and level differences.

Given Data / Assumptions:

• Poles of 2 m height set along tentative centerline.
• Markings or notations are used to guide the survey team.

Concept / Approach:Reconnaissance aims to choose the most feasible alignment with acceptable gradients and earthwork. Poles/pegs convey directional control (bearing), spacing (distance), and relative elevation (grade), enabling quick visualization of longitudinal profile against terrain.

Step-by-Step Solution:Direction marks ensure continuity of the intended centerline.Distances between pegs assist in chainage and spacing decisions.Relative elevations indicate rises/falls, controlling gradient limits.Therefore, the notations convey all three aspects.

Verification / Alternative check:Field practice routinely logs bearing, chainage, and reduced levels during reconnaissance; the pole markings mirror these essentials.

Why Other Options Are Wrong:Any single item alone gives an incomplete picture of grade-line feasibility.

Common Pitfalls:Failing to reference a benchmark; inconsistent spacing leading to poor gradient estimation; ignoring sight distance constraints while marking.

Final Answer:all the above