If you are keen to see the oldest surviving wooden bridge you have to visit the city of Lucerne in Switzerland. But if you prefer to see an example of modern bridge building, you should direct your steps to The Netherlands. At the Lunetten interchange you will find the longest hybrid composite bridge in the world. The 140m long bridge which crosses the busy A27 motorway has been developed by DSM, civil engineering and construction company Heijmans and composite construction company FiberCore Europe.
In the course of time the development of bridges proceeded from either stones or wood to iron and a mix of steel and concrete. Innovations in construction technology and architecture made bridges increasingly capable of handling demands of traffic or spanning greater distances. Replacing concrete with composites can reduce the bridges’ weight without compromising the structural integrity or load-bearing capacity. Building a bridge using composites can also lower construction and maintenance costs since both installation and upkeep takes less time compared to concrete bridges. The construction of a concrete bridge may take weeks or months. Composite bridges, in contrast, can often be installed in a couple of days.
Composite versus concrete
Today virtually all bridges are made from steel and concrete. These materials have been the traditional choice for building the heavy, sturdy structures capable of carrying mass tonnage. But concrete bridges are both time consuming and heavy to install and thereafter need regular maintenance.
Thus bridge builders are looking for alternatives: lightweight glass fibre reinforced composites are based on polyester or vinyl resins reinforced with fibre glass. They are stronger, easier to maintain and need to be replaced less often than concrete despite being up to three times lighter than steel and concrete and offering large design freedom. DSM claims that it is possible to get an entire road bridge into position in a single hour (light traffic bridge). For a heavy traffic bridge like the one over the A27 motorway this can be as low as 48h.
Building the bridge
The soil at the bridge’s location gave cause for concern about whether it was sufficiently strong to support a traditional concrete and steel bridge. It was clear that the technical challenges of the bridge and the ambitious weight and cost objectives set by Heijmans could not be achieved by a conventional bridge. The chosen solution was a hybrid bridge, featuring a deck based on composite and steel structure. The deck panels were manufactured using fibre glass composite made with DSM’s resin. In total 55t of resin was used to produce the deck panel with a customised infusion adhesive developed to glue the composite decks to the steel frame. Due to the specific design requirements the steel was not fully replaced. Hence the name ‘hybrid bridge’.
In early March 2012, the 140m long traffic bridge was installed in less than 48h, in one piece, over a weekend by civil engineering and construction company Heijmans. The lightweight structure required less construction equipment and increased the installation speed, ensuring minimal traffic disruption while reducing the costs for this final phase of the project. Interference with ongoing traffic was kept to a minimum during this very smooth installation, which was directly linked to the low bridge weight. The bridge is three times lighter than a concrete and steel alternative and can carry traffic in the heaviest 60t weight class.
More than 100 composite bridges in the world
The bridge over the A27 motorway is only one of many composite bridges that have been constructed by FiberCore Europe using DSM’s resins. This cooperation has resulted in the development of “InfraCore Inside” composites, a patented lightweight glass fibre reinforced composite. Simon de Jong, Director of FiberCore Europe said: “In total, around 100 bridges have been placed in Western Europe, US and China. This number includes many different types, including a bridge that floats on water and a moveable heavy traffic bridge, and shows that composite bridges are able to serve many different customer needs.”
Bridging of the future: “bio bridges”
DSM is already focusing on new ways for bridges and composite resins through the use of partially bio based raw materials. As emerging economies industrialise and urbanise, composite resins could be used in up to 20% of all new bridges by 2030. One example is the world’s first biological fibre reinforced polymer bridge which has been installed in the Eendragtspolder near Rotterdam, The Netherlands, on October 10, 2012 in only 15minutes. FiberCore Europe has applied the resin that was developed by DSM. After the installation of this bridge, the company reported that increasing interest had been shown in the technique, and they expect to place more of these bridges in the second half of 2013.
The project’s main contractor was GMB Civel B.V. The project was a cooperation between the Province of South Holland, the councils of Zuidplas and Rotterdam, District Water Board Schieland en de Krimpenerwaard, and the Rottemeren leisure area. Realisation: G.Z-H.