“The post-tensioned footbridge system has been designed by Arup, with Mabey becoming the first licensed distribution partner. The bridge is designed to be assembled in hard to reach sites where large cranes or heavy machinery cannot be used. Part-funded by the Rail Safety & Standards Board (RSSB) the modular bridge is expected to be of particular interest to the rail industry, providing a safer alternative to level crossings where traditional pedestrian bridges cannot be installed.
“The first bridge has been installed at a site of special scientific interest for Network Rail in Oxford. The bridge modules were light enough to be transported by an articulated lorry and then assembled on site and lifted from a distance.
“Based on Arup’s concept, Mabey is launching the bridge to its customers under the brand name Pedesta. Modular and customisable in its form, material, colour and finish, the Pedesta bridge is made up of one-metre-long modules that are fixed together with bolted shear connectors and then post-tensioned. The system allows spans of up to 30 metres.
“As the modules are 70% lighter than steel, they require only a pallet truck or forklift to move. The polymer material is also designed to be resistant to fire, graffiti, vandalism, and ultra-violet radiation…”
http://www.theconstructionindex.co.uk/news/view/mabey-launches-plastic-modular-bridge
While it may be the first example of this particular modular type, this is definitely not the first plastic bridge over a railway. An earlier example is Dawlish station footbridge, erected in 2012 at the famous seaside location. That is claimed to be the first Grade 2 listed plastic bridge!
http://www.rail.co.uk/rail-news/2013/new-plastic-station-footbridge/