With this design, the main girders are made from laminated timber and arranged under the surface of the walkway. In order to achieve optimum protection against weathering, they have a sheet metal cover on their top section and timber casing on their sides.
Timber decking, mastic asphalt and large format natural stone slabs can be used for the road surface.
The timber or steel railings are attached to the side of the main girders, equipped with cover decking on the top.
Systems that are more sophisticated such as timber-concrete composite bridges or block beam bridges are also deck bridges.
With timber-concrete composite bridges, the structural protection of the timber is ensured with the concrete slab. With block beam bridges, the road surface (with a stone or asphalt road surface) or a sealing level arranged above the girders provides protection against weathering.