Lorraine railway viaduct, Railway viaduct in Bern, Switzerland

The Lorraine railway viaduct is a 1,092-metre reinforced concrete structure carrying four tracks of the Olten–Bern line over the Aare. It is made of four consecutive bridges: the 400-metre Talwegmulde viaduct, the 199-metre Lorraineplateau viaduct, the 327-metre Aare bridge with a 150-metre main arch, and the 199-metre Schützenmatt viaduct.

Built between 1936 and 1941 by the Swiss Federal Railways as part of a four-track realignment of the Olten–Bern line, the viaduct replaced the Rote Brücke of 1858, which could no longer carry two trains at once. On 12 June 1941 it was load-tested with twenty steam locomotives. At opening it was Switzerland's longest railway bridge, a title it lost in 1969 to the 1,126 m Hardturmviaduct.

The bridge's official railway name is simply Lorraine, without the word Viadukt; the neighbourhood on the north bank of the Aare carries the same name. The parallel road crossing, the Lorrainebrücke, sits just upstream and lets pedestrians look along the 327-metre Aare span. The structure is listed as a Swiss cultural property of cantonal or local significance.

The viaduct carries the Olten–Bern line across the Aare just north of Bern station, so a train seat on that stretch gives a view over the river. Upstream alongside it runs the Lorraine road bridge, from which the 150 m main arch and its 33 m rise can be seen. The structure is split into four bridges, from the 400 m Talwegmulde viaduct to the 199 m Schützenmatt viaduct.

The viaduct's main Aare span is a 150-metre reinforced concrete arch with a 33-metre rise, built on a free-standing timber falsework of twelve trusses spanning 146 metres. On 12 June 1941, twenty steam locomotives stood on the new bridge as a load test. It lost the title of Switzerland's longest railway bridge in 1969 to the 1,126-metre Hardturm viaduct.