Upon completion of the causeway, a punt operated across the deep, navigable section of the river, but could not cope with traffic demands. To resolve this issue, the first bridge across this point of the Derwent opened in 1849. The bridge was designed by the firm of architect and former convict James Blackburn. Being a swing bridge, it could pivot out of the way to allow ships to pass. In the late 1870s, the Tasmanian Main Line Railway called for modifications to the causeway so they could lay tracks over it. The causeway required widening and the swing bridge was modified as well.