| Composite bridges are also inherently buoyant, making them ideal for marine and swampy environments. Composite bridges have a life expectancy of more than 100 years, about twice as long as a conventional one. A composite bridge with better load bearing capability and lower weight compared to steel and concrete has been demonstrated by FiberCore Europe and DSM Composite Resins. It was designed for the Chinese market and incorporates a hand-rail found on a traditional Chinese footbridge. All components of the bridge are made from glass fiber reinforced plastic. The composite bridge is said to weigh about 5% of the weight of traditional concrete bridge and 20% of a steel bridge with the same dimensions and loading capacity. This lower weight means that less substantial foundations can be used, transportation is easier, and installation does not require heavy lifting equipment and is therefore quicker. It is not only strong enough to withstand the regulation emergency vehicle weight of 6 tons, it could even take a vehicle weight of up to 30 tons.
Spanish construction firm ACCIONA Infrastructure worked with Huntsman Advanced Materials to construct a 44 m long, 3.5 m wide carbon composite pedestrian bridge in Madrid. The 44m long, 3.5m wide carbon composite pedestrian bridge was to be built over the Manzaneres River and therefore needed to be made as a single structure. The challenge lay in designing a load bearing, single piece structure that was also lightweight so as to meet the transportation, logistics and installation requirements. As the installation site was in the city centre, space limitations and the need to limit disruption meant the constructors were allowed a maximum of 4 hours to install the bridge onsite. From the initial fibre placement to the demoulding and finishing processes it took a total 30 days to manufacture the bridge. The structural load bearing bridge beam was built utilising 12 tons of carbon fibre. The smoother and more aesthetically pleasing surface of the bridge offers excellent corrosion resistance, less maintenance. The carbon composite beam weighs only 25 tons, it was installed in less than 2 hours using a 75 ton crane. Because no joints, assembly or high capability cranes are needed for either installation or maintenance, the composite bridge reduces onsite plant requirements and opens up installation opportunities in a host of different locations.
Axion International, known for creating recycled plastic composite bridges that can support military tanks and trains, has executed a pedestrian bridge in Fort Lee, Va. Similar to the company�s larger bridges, but on a smaller scale, the pedestrian bridge was built in a factory and shipped whole to the site, where it was dropped into place. For its recycled structural composite, Axion collects post-consumer plastics, mostly high-density polyethylene (HDPE), combines them in a proprietary mixture, heats then extrudes them into structural forms such as I-beams, marine pilings and railroad ties. Accelerated ageing tests have indicated that the material is not subject to degradation from moisture or other environmental elements, is fully recyclable into more lumber at the end of its life in the field. A team of scientists at Rutgers University helped develop the material, which resists creep, or the long-term deformation of the material under heavy loads. The material is creep-resistant up to 600 lbs/square inch (straight HDPE creeps at 60 lbs/square inch.)