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Incremental launch is a recent method of building a complete bridge deck from one end of the bridge only.
Contents
History
The first incrementally-launched bridge was the 96 metre span Caroní River Bridge, a box girder bridge over the Caroní River in 1964.
The normal method of building concrete bridges is the segmental method, one span at a time.
Method
The bridges are mostly of the box girder design and work with straight or constant curve shapes, with a constant radius. 15 to 30 metre box girder sections of the bridge deck are fabricated at one end of the bridge in factory conditions. Each section is manufactured in around one week.
The first section of the launch is not made of concrete, but is a stiffened steel plate girder and is around 60% of the length of a bridge span, and reduces the cantilever moment.
The sections of bridge deck slide over sliding bearings, which are concrete blocks covered with stainless steel and reinforced elastomeric pads.