Setting out of Alignment and achieving design embankment profile

Guidelines for setting out of alignment, construction limits and achieving design embankment profile for highways.

1) Introduction

Sometimes in case of Expressways, National Highways and New Village roads specially under T6 head (Greenfield projects), (No wonder whatever type of road it may be, Basics remains the same 😌) setting out of alignment, construction limits and achieving design embankment profile is necessary.

Site Visit before Estimate Preparation

Current Site situation

Detailed guidelines already exist in IRC publications – IRC SP-19 (Survey Manual) and IRC:36 (Earth Embankment). Field engineers must refer original documents for accuracy.

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2) Setting out of alignment

2.1 Staking the final centre line

2.1.1 Final location survey is done using transit theodolite and levelling. 2.1.2 Central line translated on ground. 2.1.3 HIP & POT fixed with concrete hubs or spikes.

Fig 1(a) Reference pegs at HIP & curves

Fig 1(b) Reference pegs at POT

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3) Setting out construction limits

Reference pegs fixed 20–25m away. Intermediate pegs @50m (plain) & 20m (curves). Hilly terrain spacing reduced.

Fig 2 Batter pegs defining embankment limits

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4) Staking and profile making

4.1 Alignment marking using pillars 4.1.2 Profile marking using painted poles 4.1.3 Sequence of laying layers

Fig 3.1 Expected final structure

Fig 3.2 First Layer

Fig 3.3 Second Layer

Subsequent layers placed only after full compaction. Extra earth at edges trimmed after completion.