Incremental Launching

Incremental Launching

In this method of construction, the bridge superstructure is assembled on one side of the obstacle to be crossed and then pushed longitudinally (or “launched”) into its final position. The launching is typically performed in a series of increments so that additional sections can be added to the rear of the superstructure unit prior to subsequent launches.

This method is particularly suitable for the construction of continuous post-tensioned multi-span bridges. It consists of casting approx. 15 m to 30 m long sections of the bridge superstructure in a stationary formwork behind an abutment to push a completed section forward with jacks along the bridge axis. The sections are cast contiguously, one after another, and are then stressed together. The superstructure, growing section by section is launched over temporary sliding bearings on the piers until the bridge is completed.

Incremental launching may often be the most reasonable way to construct a bridge over an inaccessible or environmentally protected obstacle.