Construction methods · Piers, pylons and abutments

Integral and semi-integral abutments

The deck is cast into the abutment so there is no expansion joint and no bearing at the ends; the abutment moves with the deck on flexible piles or a sliding sleeper. No joint means no leak, no bearing replacement and lower whole-life cost: the game rewards it in the upkeep score.

How bridges get built · Piers, pylons and abutments · Integral and semi-integral abutments

Also called: jointless bridge, integral bridge, semi-integral abutment

Concept diagram (TheBridgeEng)

How it is done

Drive a single row of steel H-piles (weak axis) or small-diameter piles in a sleeved trench to allow movement.
Cast the abutment stem and the deck end in one pour, embedding the girders.
Backfill with compressible or elastic material behind the wall; provide a long approach slab sliding on the fill.

Where it fits

Bridges up to about 60-120 m long and 30 degrees skew, moderate climates, steel or concrete girders.

Where it does not

Long bridges with large thermal movement, high skews, very stiff foundations that cannot flex.

Plant, pace and money

PlantPiling rig, formwork, standard concrete plant.

ProductivitySimpler and faster than seat abutments.

Cost5-15 % cheaper to build and much cheaper to maintain.

Risks and controls

What goes wrong

Ratcheting of backfill pressures over years, cracking at the deck-abutment junction, approach slab settlement.

Quality assurance

Pile orientation and flexibility checked, junction reinforcement detail inspected.

Examples

Standard in the UK, Sweden and much of the US for short bridges; the game bonus for jointless short bridges reflects it.