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UNDERLANE BB FT

Travelling Formwork System for Free Cantilever Construction

BRIDGEBUILDER Enhance The Economic Performance of Bridge Projects.

Reliable Bridge Construction Equipment for Free Cantilever Construction with NRS Innovation and Solutions.

“BRIDGEBUILDER” FORMTRAVELLER

The Underlane NRS Formtraveller which is widely and well known as the Bridgebuilder, is the most reliable and extensively used FormTraveller system in the world for in-situ construction of free cantilever post tensioned box girder bridges as well as cable-stayed concrete bridges.

It has been adopted as the de facto design that is widely used among all suppliers in the industry.

To date NRS has supplied more than 900 units of Bridgebuilder worldwide.

The “Bridgebuilder” formtraveller system was invented in 1970 and today it is acclaimed for enhancing the cost-effectiveness of bridge projects worldwide.

The Bridgebuilder has undergone vast improvements over the years and incorporated innovative solutions, making it a developed, practical and reliable system for contractors.

Today the Bridgebuilder is a versatile, lightweight, easy-to-assemble and operate.

The system is designed with the following cost savings solutions:

  • Special “Fast-Split” installation method on hammerhead as short as 7m long.
  • NRS Bridgebuilder with cross member for Hammerheads as short as 3m.
  • Back launching to pier for ease of dismantling after use
  • Use of Bridgebuilder for casting hammerhead
  • Casting closure segment stitches.

 

STANDARD CONVERTIBLE BRIDGEBUILDER

The Standard Bridgebuilder is designed for a maximum segment length of 5 m and load capacities (concrete and formwork) varying from 100 tons to 400 tons. The steel weight depends on the cross-section of the bridge in question, but will normally vary from about 25 tons to 65 tons correspondingly. The Standard Bridgebuilder may be adapted to suit almost any cross-section, and is easily adjustable during operation to variations in segment length (up to 5 m), section height, web thickness, and deck width.

 

TAILORED BRIDGEBUILDERS

The Bridgebuilder may be tailor-made for segment lengths beyond 5 m and other extreme conditions. Alternatively it may be designed for shorter lengths where the maximum segment length is less than 5 m, and there is a requirement to reduce the weight of the Bridgebuilder for a particular application.

NRS Special Bridgebuilder for arch bridge construction has also been used successfully for the construction of the 323m arch bridge at the Hoover Dam Bypass project – the longest arch bridge in North America and the 4th longest concrete arch bridge span in the world.

Modern bridges are becoming wider and longer but at the same time clients and contractors are seeking shorter construction time. In NRS, pursuing improved and innovative solutions to meet these requirements has always been one of NRS main goals.

NRS never fails in giving innovative designs even for conventional equipment like the Formtraveller

THE BRIDGEBUILDER FEATURES

  • Lightweight

The use of rectangular hollow sections in the main structural components and recoverable high strength bars in all stays and ties reduces the total steel weight to a minimum.

  • Versatile and Flexible Design

The Bridgebuilder may be adapted to almost any cross-section and is easily adjustable during operation to variations in segment length, box height, web thickness, deck width and road alignment (gradient, curvature, super-elevations).

  • Small Deflections

The vertical deflection at the front of the Bridgebuilder is less than 25 mm at maximum load. Formwork beams are designed for a maximum deflection of 1/400 of their length.

  • Easy Assembly and Operate

-One Bridgebuilder may be assembled in one week. Rolling forward on rails, the reset time is short.

-Lifting system to lift and install the whole  pre-assembled on ground Underlane BB FT.

– Rebar Carrier and trolley system

 

SPECIFIC DETAILS

A normal working cycle may be as follows:

  • The Bridgebuilder, except for the internal formwork, is launched into position for a new segment
  • The external formwork is levelled and fixed.
  • Bottom slab and webs reinforced.
  • The internal forwork is pulled forward.
  • Concreting of bottom slab and webs. The top slab may be cast after a short intermission to allow setting of the concrete in the webs, or it may be cast the next day.
  • After sufficient concrete curing, post-tensioning takes place.
  • Form work is loosened, and the Bridgebuilder launched forward to the next segment. In most cases one cycle is carried out in one week. There are examples of 4-5 days cycle.

MAIN PRINCIPLE & COMPONENTS

POSITION PHASE DESCRIPTION
Upper Left 1 Assembly at pierhead as small as 3m
Lower Left 2 Concreting of 1st segment on each side of the pier finished
Upper Right 3 Splitting of travellers (bridgebuilder)
Lower Right 4 12,2 m concreted (standard bridgebuilder); ready for normal procedure

When the pier head is too small to allow normal assembly of the Bridgebuilder, our patented Cross-member solves the problem. It makes it possible to start free cantilevering from pier heads as small as 3 m. The procedure is illustrated through the above 4 phases.

LIFTING OF SEGMENT

POSITIONING OF SEGMENT

 

The Precast Segmental Bridgebuilder is equipped with two hoists for lifting the precast segments as well as for adjusting the crossfall. A manipulator permits adjustment of the longitudinal fall and hydraulic cylinders launch the device forward.

Some of the world’s most outstanding bridges have been built by use of the NRS Bridgebuilder Formtraveler. Refer to the table below.

No.

Project

Country

Span (m)

Construction

Supplier

1

Stolmasundet bro

Norway

301

1998

NRS AS

2

Raftsundet, Lofoten

Norway

298

1998

NRS AS

3

Sandsfjord Bridge

Norway

290

2014

NRS AS

4

Humen, Pearl River

China

270

1997

5

Varrod bro, Kristiansand

Norway

260

1993

NRS AS

6

Kristallopigi

Greece

260

2002

NRS AS

7

Gateway bridge, Brisbane

Australia

260

1986

NRS AS

8

Skye bridge

UK

250

1995

9

Ponte San Joao , Porto

Portugal

250

1991

NRS AS

10

Talübvergang Schottwien

Austria

250

1989

11

Northumberland Strait Crossing

Canada

250

1997

12

Chevire Viaduct, Nantes

France

242

1991

13

Norddalsfjord bro

Norway

231

1987

NRS AS

14

Stovset bro

Norway

220

1993

NRS AS