Ultimo Road Railway Underbridge, Railway bridge in Ultimo, Australia.

Ultimo Road Railway Underbridge is a half-through, triple-girder plate-web bridge: three riveted wrought-iron main girders, one between the two former tracks, carry wrought-iron cross beams. Brick abutments stand on the north and south sides of Ultimo Road. Cast-iron columns on the kerb lines, inserted around 1900, divide the original 21.64-metre span into three: 3.96 metres over each footpath and 13.72 metres in the centre.

Built in 1879 by the New South Wales Public Works Department, this structure replaced an earlier timber bridge from 1855 that could no longer handle growing cargo volumes. Around 1900 additional cast-iron supports were added to carry heavier locomotives and greater loads.

The structure shows how engineers of that era solved problems posed by expanding cargo transport to the harbor. Visitors can see the craftsmanship in the metalwork and understand how central port trade was to the city's growth.

The structure is part of the urban rail network and can be viewed from the public way that passes over it. The best views of the work appear from below or the sides, where the metal components and supports are clearly visible.

The unusual construction feature of this bridge is a central girder that runs exactly between two railway tracks, creating the visual impression of two separate bridges sharing one support. This design allowed builders to reduce material costs while still supporting both rails effectively.