Various further superstructure items – kerbs, handrails and balusters, for instance, are usually attached more or less directly to the deck, and these can conveniently be taken into account at this stage. We also sometimes need to consider ramps and steps or external stairs made from timber,



Figure 6.1 A: a simple open-boarded deck, using pressure preservative treated Scots pine; note also the handrail posts and parapet extended from flitched-in steelwork sandwiched between the glulam carriage beams – Vercors, France. B: a more sophisticated sealed deck using modern technology – this is a block laminated deck, using a 220 mm deep layer of glulam, followed by a membrane, then a 40 mm plate of Kerto LVL, sealed with a bitumen felt and a two-layer mastic asphalt system; in case of partial breakdown of the waterproofing, there are drainage collection points and downpipes – a true ‘belt and braces’ system – Tharandt Botanical Gardens walkway – see case study in Chapter 9 Photo A: © CJM Photo B: © Schmees & Lühn

and for convenience these too are included. In general, the roofs of fully covered bridges follow the main principles for those on other buildings. However, some of the shapes and coverings that are especially useful for bridges are shown, together with guidance on the necessary shelter angles at the eaves, and some brief discussion of how the roof may assist the overall stability of the bridge.