What is incremental launching method?

The basic idea of the incremental launching method is to prefabricate bridge girder segments behind an abutment and to launch the increasing bridge span by longitudinal hydraulic jack and make it slide on  bearings into the final position without the aid of scaffolding.

The inremental launching method is widely used in construction for continuouse deck bridge and cable-stayed bridge which are of prestressed reinforced concrete structure.

To reduce cantilever moment on the concrete girder, a launching nosed is fixed at front end of concrete girder, usually the length of launching nose if 0.6-0.7 times of the bridge span. With a large span > 50m, usually the temporary piers shall be needed.

The necessary parts for incremental launching method:

1. hydraulic jacks for launching the bridge span

2. sliding bearings to slide the bridge span

3. launching nose to help reduce cantilever on the bridge girder