12371 TASMAN HWY, SWANSEA
TASMAN HWY, SWANSEA

Spiky Bridge is a distinctive, dolerite random rubble road bridge or causeway across Lafarelles Gully. The side walls of the bridge are topped with hundreds of vertically mounted large dolerite spalls up to 30 centimetres long, the appearance of which gives it the popular name the Spiky Bridge. The gully’s intermittent stream flow is directed by two mortared stone wings on the bridge’s upstream (westerly) side through a narrow arched opening or culvert in its base. Jagged dolerite stones have been used at the highest point of the segmental arched opening, giving it a spiky appearance in sympathy with the palisade above. The six-metre-wide carriageway has a central drainage opening on each side. Below the carriageway on the downstream (eastern) side is a steeply sloping drystone buttress comprised of flat dolerite stones packed horizontally. This buttress, which was added in 1923 to strengthen the bridge, has two stone drainage features constructed with cement mortar: the archway (culvert), and a vertical channel draining the carriageway above. The bridge was constructed with shell lime mortar.



Spiky Bridge and its surrounds may include surface and subsurface deposits related to stone working and quarrying activities that have the potential to yield information that contributes to an understanding of the construction of the bridge and its 1920s buttress, as well as the skills and labour practices of the convict workforce and workers involved in the later buttressing and repair works.