LAUNCHING GANTRIES

An advance, fast and reliable solution for extreme tight radius erection of modern pre cast segmental bridges.

NRS Launching Gantry (LG) System – The recognized technology for construction of modern bridges with tight horizontal radius and has become one of the most widely used for the construction of precast segmental bridges.

NRS had grown rapidly its reputation as one of the most recognized suppliers of Launching Gantries for “Span by span” and Balance cantilever methods of construction.

Several features that makes our system more widely acceptable by contractors with remarkable success in many challenging bridge projects worldwide includes:

The use of “Hinge” solution to overcome bridges with tight horizontal curves, including a specially designed gantry crane for the kinked hinges.
“Glue-as-you-go” concept for wet joints segmental bridges to reduce double handling of segments.
“Turnaround” concept to reduce stacking of segments within a span.
Unique Gantry crane structure to enable smooth movement around hinges
Fail-proof hydraulic launching system.

HINGE LAUNCHING GANTRY (LG) – An Innovative Solution for Curve Bridges

To overcome the difficulties of erecting spans on curve with the conventional straight LG, NRS developed in the early 90’s the innovative “hinged” concept, which allows the articulation of the LG to handle segment erection and launching operation. The hinge concept enables span erection on horizontal radius as small as 75m (40m span) previously never thought it is possible without the need of additional external temporary supports.

As many as 6 hinges, each regulated by hydraulic cylinders, have been used in a single LG. A specially designed gantry crane is also used to travel smoothly through the kinked hinges along the LG during lifting and placing of segments.

The hinge concept remains today a unique feature well known in the industry for erection of precast segmental bridges on tight curves. This solution has been proven successful in many major projects particularly in Metro or Light Rail Transit projects where tight curves are quite common along the alignment. The hinged LG offers significant advantages over the conventional straight gantries in terms of erection speed and cost of construction.

SPECIFIC DETAILS

The UNDERLANE Launching Gantry

TYPICAL ERECTION METHODS, CONDITIONS AND FEASIBILITIES

Our gantries (LG) can be used for both balanced cantilever as well as for infill span-by-span erection. Depending on the project dry joint or wet joint erection is required.

1. Featuring segmental bridges with dry or glued joints, using erection methods like infill-spans and balanced cantilever.

2. Special hinged underlane gantries (with up to 12 hinges) have been supplied to accommodate tight horizontal curvature, down to 75m radii.
3. Use of separate centre-beam to accommodate erection of separate parallel double and triple tracks as well as bifurcation spans.
4. Vertical climbing of gantries to accommodate tight vertical curvature and steep longitudinal fall.
5. Partly and fully final post-tensioning carried out while the whole span is still supported by the gantry, without need to use a special plunger arrangement at each end.
6. “Glue-as-you-go”, erecting segments without any or only limited double handling of segments.
7. Balanced cantilever and infill-span erection with same gantry.
8. Cranes capable of walking through hinged transitions (also noses).
9. Gantry can lift and adjust whole span in level and line (vertical and transverse adjustment).
10. Gantry is selflaunching, transports also supports by its own crane.
11. Aux. equipment for erecting pre-cast wings at 2nd stage (if needed).

SPECIAL FEATURES

1. SF-UL-LG - Supporting... — Supporting Bracket installed on both standard pier and straddle bent (station area)

2. SF-UL-LG - Hydrauically.. — Hydraulically adjustable hinge (1 of up to 7) to lay out spans/launch at radii down to as little as 75m

The OVERHEAD Launching Gantry

TYPICAL ERECTION METHODS, CONDITIONS AND FEASIBILITIES

Our gantries (LG) can be used for both balanced cantilever as well as for infill span-by-span erection. Depending on the project dry joint or wet joint erection is required.

1. Featuring segmental bridges with dry or glued joints, using erection methods like infill-spans and balanced cantilever.
2. Special hinged overhead gantries (with up to 6 hinges) have been supplied to accommodate tight horizontal curvature, down to 100m radii.
3. Side-launching of gantry to accommodate erection of separate parallel double and triple tracks, as well as bifurcation spans.
4. Vertical climbing of gantries to allow access for side shifting to neighbouring bridges, and to accommodate tight vertical curvature and steep longfall.
5. Fully and partly final post-tensioning carried out while the whole span is still suspended to the gantry, without need to use special plunger arrangement at each end.
6. “Glue-as-you-go”, erecting segments without any or only limited double handling.
7. Balanced cantilever and infill-span erection with same gantry.
8. Cranes capable of walking through hinged transitions (also noses).
9. Gantry can lift and adjust whole span in level and line (vertical and transverse adjustment).
10. Gantry is selflaunching, transports also supports by its own crane.
11. Aux. equipment for erecting pre-cast wings at 2nd stage ( if needed).