Construction methods · Caissons and marine foundations

Floating barges and spud barges

A flat-top barge with a crane, held by spuds (vertical legs dropped into the bed) or anchors. The cheapest way to put a rig or crane over water, and the most weather-sensitive: it moves with the waves and the tide, so precision work waits for calm.

How bridges get built · Caissons and marine foundations · Floating barges and spud barges

Also called: work barge, spud barge, crane barge

Floating barges and spud barges — concept diagram — Concept diagram (TheBridgeEng)

How it is done

Position with tugs, drop spuds or set anchors; deck the crane and the rig.
Drive piles through a template fixed to the barge or to previously driven piles; adjust for tide.
Move between piers in hours.

Where it fits

Sheet-pile cofferdams, driven piles in rivers and sheltered water, pier construction in calm estuaries, service of jack-ups.

Where it does not

Open sea, strong currents, bored piling that needs a fixed platform, tolerances tighter than the barge motion.

Plant, pace and money

PlantFlat-top barge 30-80 m, 100-300 t crawler crane, spuds, tugs.

ProductivityCheap to move, slow to hold position; downtime in weather.

CostUSD 5,000-25,000 per day.

Risks and controls

What goes wrong

Capsizing under an over-swung crane, spud failure in current, collision, crew falls.

Quality assurance

Stability calculation for each crane radius, mooring plan, weather limits.

Examples

River pier cofferdams worldwide; the game's default access for water piers under 6 m.