Puente ferroviario Carmen de Patagones - Viedma, Railway and road bridge in Carmen de Patagones, Argentina.

The Carmen de Patagones–Viedma railway bridge, known locally as Puente Viejo, crosses the Río Negro over 268 metres of steel on three pillars. It has four spans: two fixed on the north bank, a 52-metre bascule span and a 46-metre shore span. The control cabin sits above the deck, and the roadway is asphalted.

Work began in 1927 on two abutments and three piers; in 1929 the German firm Dyckerhoff & Widmann took the foundations, Mario José Rovere directed the project and Gutehoffnungshütte built the four steel spans, shipped from Germany in pieces. Over 150 workers laboured around the clock in 8-hour shifts. The bridge opened on 17 December 1931, when a crowd walked across from Patagones to Viedma.

Locals call it Puente Viejo. Until 1957, Don Rosario Dominicci operated the hydraulic counterweight lift to keep it from rusting, raising it for the last time that year after the steamer Patagonia passed in 1943. Honeymooners on the Plaza Constitución–Bariloche train threw coins into the Río Negro for family prosperity; since 2013 couples lock padlocks on the footbridge railings and throw the keys into the river.

The bridge is accessible to pedestrians and cyclists with a dedicated pathway alongside the railway and road sections. Visitors should note that active train traffic may affect pedestrian access at certain times.

The central pillar holds a demolition charge point built in because the steelwork came from Germany; two divers inspecting the pillar found it in 1971. Only two hydraulic counterweight bascule bridges were ever built, and the other, in Japan, was destroyed in World War II.