Reference pillars along a proposed road centre line – what do they record? Reference pillars fixed on the surveyed centre line of a proposed road typically provide which of the following information?

Introduction / Context:
During highway location and setting out, reference pillars serve as durable markers of design geometry and elevations. They help transfer alignment and level data from the survey to construction.

Given Data / Assumptions:

• Pillars are placed along the proposed centre line.
• Site requires recovery of alignment and vertical control.
• Contract drawings show design formation levels and offsets.

Concept / Approach:
A complete reference pillar record typically includes chainage (R.D.), the reduced level (RL) at the pillar, and notes on required formation level (FL). Where required, offsets from the centre line to edge or features are also referenced for setting out.

Step-by-Step Solution:

Verification / Alternative check:
Field books and pillar plates routinely combine these parameters so crews can re-establish line and level quickly.

Why Other Options Are Wrong:
Each of A–D is commonly included; hence “all the above” is the best choice.

Common Pitfalls:
Letting pillars get disturbed without redundancy; omitting RL or FL which complicates earthworks.

Final Answer:
all the above