Subgrade Grading and Compaction

The Surface Is the Handover

The surface is the handover between operations. An excavator may finish its excavation, but the roller still needs suitable material, lift thickness and moisture. A scraper may finish shaping, but the irrigation operator still needs a connected fall to a usable outlet. Define acceptance at each transition instead of allowing the next machine to inherit an unresolved problem.

Before moving material

Name the operation that receives the surface and agree its requirements.

Receiving operation and checks

Release the area to the next operation only after outstanding defects are identified. Use independent level checks and project-specific material tests where required.

Visual smoothness alone does not prove compaction, bearing capacity or hydraulic performance.

Uneven Subgrade

Uneven subgrade can create variable thickness in every layer above it. Correcting the surface is useful only if the underlying support is acceptable.

Before moving material

Identify soft areas and compare formation levels with design.

Receiving operation and checks

Complete compaction and specified acceptance checks. Check levels before base material conceals the subgrade.

A scraper does not replace proof testing or project-specific investigation.

Prepare for Compaction

Preparation for compaction ensures that the compactor receives suitable material in the intended layer arrangement. Grading and moisture conditioning must fit the project requirements.

Before moving material

Confirm material, layer depth and compaction method.

Receiving operation and checks

Compact and test according to the brief. Inspect edges and areas inaccessible to the main compaction plant.

There is no single pass count or moisture target suitable for all materials.

Record the job inputs

Use this checklist to turn the scenario into a specific brief. Retain the design revision and agree who accepts each completed layer.

• Existing condition, extent and the reason for intervention
• Required finished purpose, receiving operation and acceptance criteria
• Material type, layer role, source, receiving area and volume state
• Reference levels, datum, survey method and issued design revision
• Available tractor, implement configuration, travel route and turning space
• Checks before work, stopping points and evidence retained at handover

Checklist ticks apply only while this page is open. Include the completed brief in your project records.

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