First operation during the detailed survey of a hill road, is

ANS:D - fixation of Bench Marks

Fixation of Bench Marks is usually the first step in the detailed survey of a hill road. Bench Marks are permanent reference points established at regular intervals along the road alignment.

They serve as a basis for all subsequent survey measurements and help ensure accurate and consistent elevation data throughout the project. Once the Bench Marks are fixed, they provide a reference for conducting hydrological and soil surveys, adjusting the alignment, deriving longitudinal and cross-sections, and staking the ground.