- Log bridge
BridgeTypePix
type_name = Log Bridge
image_title = Footpath bridge in the French Alps near Vallorcine
sibling_names =Clapper bridge
descendent_names =Beam bridge
ancestor_names =Step-stone bridge
carries =Pedestrian s,vehicle s (on multiple parallel logs)
span_range = Short
material =Log s, dry set stonework footings, top may be flattened or boards added, topped with rammed earth for vehicles
movable = No
design = Low
falsework = No|A log bridge is abridge that uses logs that fall naturally or are intentionally felled or placed across streams. The first manmade bridges with significant span were probably intentionally felled trees. The use of emplaced logs is now sometimes used in temporary bridges used for logging roads, where a forest tract is to be harvested and the road then abandoned. Such log bridges have a severely limited lifetime due to soil contact and subsequent rot and wood-eatinginsect infestation. Longer lasting log bridges may be constructed by using treated logs and/or by providing well drained footings of stone orconcrete combined with regular maintenance to prevent soil infiltration. This care in construction can be seen in the bridge illustrated, which has well locked dry set stone abutments and a footpath leveled with boards.
Wikimedia Foundation. 2010.