The following illustrations show various types of bridge suitable for rural paths. Construction details are given later in the chapter. The dimensions of timbers are not given as these must be calculated for each site from the information given here.
Simple bridges
These are low bridges without handrails, suitable for situations where there is no risk to safety.
Clapper
Stone clapper bridges are an ancient type of bridge, which can only be constructed where large enough slabs are obtainable nearby or can be brought to the site. A modern equivalent which retains something of the style of a clapper bridge can be built with railway sleepers fixed to mortared piers. This is similar to a boardwalk, but raised on piers to cross flowing water.
Sleeper
Duckboard
For short spans, the duckboard can be prefabricated. See here for methods of fixing the duckboard to the half-sleepers.
Bridges with handrails
Single beam
These are suitable for footpaths in locations where use by wheelchairs is not possible. They are economical in materials, and with their simple line and ‘monkey-bridge’ appearance, they fit well in remote and adventurous landscapes.
Either a V or square section beam can be used. As shown below, the beam can be anchored either to a cast concrete end seat, or into an abutment.
Log bridge
These are best used at sites where logs are locally available. Handrails must always be raked to give a secure fixing.
Sawn timber bridge
This is the standard type of bridge for footpaths. Two or three beams are used, according to the span and the required width. Steel ties through the width of the bridge hold the handrail posts in position. Struts are skew nailed next to each tie to give the structure rigidity.
Deckboards can either be flush with the beams, as shown, or overlapped by about 50mm, and cut to fit around the handrail posts.
