Construction methods · Heavy lift, moving and accelerated construction

Rotation (swing) construction

The bridge or its arch halves are built parallel to a railway or river on a pivot bearing, then rotated horizontally into position in a few hours during a possession. Vertical rotation raises arch halves built lying near the ground. A Chinese speciality now used worldwide for rail crossings where the track can only be closed briefly.

How bridges get built · Heavy lift, moving and accelerated construction · Rotation (swing) construction

Also called: rotation method, swing bridge construction, horizontal rotation, vertical rotation

live railwayspherical hingebuilt parallel to the trackrotated into place in a few hours during a possessionRotation (swing) construction
Concept diagram (TheBridgeEng)

How it is done

  1. Build a spherical hinge or a ring track under the pier; build the superstructure (or the arch half) on the pier in the rotated position, balanced by counterweight.
  2. Test the rotation over a few degrees; on the day, rotate with strand jacks or hydraulic pushers at 1-2 degrees per minute; lock and cast the closure.
  3. Vertical rotation: arch halves are lifted about a hinge at the springing with strand jacks, then closed at the crown.

Where it fits

  • Crossings of live railways and busy waterways where the possession is a few hours; spans 60-300 m; cable-stayed, arch and continuous decks.

Where it does not

  • Sites where the rotated position conflicts with anything; unbalanced structures without counterweight.

Plant, pace and money

PlantSpherical hinge (to 30,000 t), strand jacks or pushers, counterweights, survey.
ProductivityRotation in one to two hours; the rest as for the erection method chosen.
CostThe hinge and temporary works USD 1-5 million; saves the possession cost.

Risks and controls

What goes wrong

  • Unbalanced weight causing the structure to tip on the hinge, friction stalling the rotation, closure misalignment.

Quality assurance

Weighing test to find the centre of gravity, trial rotation, real-time monitoring during the swing.

Examples

Hundreds of Chinese rail crossings (up to 25,000 t rotated), Rion-Antirion piers were built afloat instead; European examples at Karlsruhe and in the UK.

In the bridge game

What Bridge Master applies when you pick it

Deck types: Steel box girder, Steel truss, Network tied arch, Steel arch, Concrete arch, Cable-stayed, Extradosed, PSC box, balanced cantilever. Spans 60-200 m, up to 300 m.

  • +40: Live railway below: build beside it and swing it in during one possession.
  • +15: The channel stays open while the span is built on the bank side.
  • -35: Nothing below to protect: rotation is money spent on a hinge you did not need.
  • -30: Short spans are lifted in a night with a crane.
  • +10: Keeps cranes and falsework out of the street.
  • not allowed: Too heavy and too long to rotate on one hinge.

Try it in the game →

Related methods

Cable-stayed cantilever erectionArch erection by cantilever with temporary staysLateral slide (slide-in bridge construction)

Further reading

Chinese rotation construction papers · IABSE reports on swing construction

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