Last reviewed 1 Oct 2026 · 6 min read
Purpose
Land development converts rough or unproductive land into arable, irrigable fields. It includes clearing, levelling, grading, bunding, terracing, excavating ponds and channels, and reclaiming ravines. Heavy earth-moving machinery performs these operations faster and cheaper than manual labour on large areas.
Classification of earth-moving machines
| Operation | Machines |
|---|---|
| Clearing (trees, bushes, stumps, stones) | Bulldozer, rake blade, tree dozer |
| Excavating and pushing | Bulldozer, angle dozer, scraper |
| Excavating and loading | Front-end loader, hydraulic excavator, backhoe (drag hoe), dragline, shovel |
| Hauling | Dump trucks, scrapers |
| Grading and levelling | Motor grader, land plane, laser-guided leveller |
| Compacting | Rollers (sheep-foot, smooth-wheel, pneumatic-tyred, vibratory) |
| Digging trenches and channels | Trencher, ditcher |
Most of these use crawler (track) tractors for high traction, or wheel tractors for speed and mobility.
Bulldozer
A bulldozer is a crawler or wheel tractor fitted with a large front blade (dozer blade) mounted on push arms and raised/lowered by hydraulic cylinders.
Types of blades
| Blade | Features |
|---|---|
| Straight (S) blade | Fixed perpendicular to the direction of travel; high digging force; for dozing, ripping and clearing |
| Angle (A) blade (angle dozer) | Can be set at an angle (up to about 25–30° either side) to side-cast the soil; used for road cutting, trench filling and sidehill work |
| Universal (U) blade | Wide, with curved side wings, carries more load over longer distances |
| Semi-U blade | Between straight and universal |
| Tilt dozer / bull-dozer with tilt | Blade tilts one side down to cut ditches, break hard soil, and cut furrows |
| Cushion blade / push blade | For pushing scrapers |
Uses
- Clearing land of trees, stumps and boulders.
- Shallow digging and pushing earth over short distances (up to about 100 m economically).
- Spreading and levelling fill.
- Making bunds, terraces and farm roads, and filling gullies.
- Ripping (a rear-mounted ripper tooth) hard soils and rock.
Output
Output (m³/h) = Blade capacity (m³) × trips per hour × efficiency factor
where trips per hour depend on the push distance, forward and reverse speeds, and time to change gears (cycle time).
Scraper
A scraper has a bowl with a cutting edge; the machine cuts a thin layer of soil, loads it into the bowl as it moves forward, hauls it to the dump site and spreads it in layers.
| Type | Description |
|---|---|
| Towed (drawn) scraper | Pulled by a crawler tractor; capacity about 6–12 m³ |
| Self-propelled (motorised) scraper | Tractor and bowl in one unit with pneumatic tyres; high speed; capacity about 10–30 m³ |
| Elevating scraper | Has a loading elevator, so it does not need a pusher |
| Tandem and push-pull scrapers | Two scrapers working together or assisting each other in loading |
- Cycle = load → haul → dump/spread → return.
- Economical hauling distance: 150–1500 m (longer than a dozer).
- Used for land levelling, borrow-pit work, tank construction, and embankment building.