Sluppen Bridge

Sluppenbrua (lit. Sluppen Bridge) is a road bridge across the Nidelva river in Trondheim, Norway. It is 82 meters long, and connects the Norwegian National Road 706 (riksvei 706) to the areas east of Nidelva.
Originally, Sluppenbrua was built as a railway bridge on the Trondhjem–Støren Line, which was opened in 1864. This bridge was around 200 m long og 30 m tall, made by timber standing on a foundations of rock. This bridge was torn down in 1884 when the new Dovre Line going by Nidareid was opened. The foundations were transferred for free to the Norwegian Public Roads Administration in 1927 with the intent to build a road bridge on the same spot.
The new road bridge was postponed, resulting in the first road bridge to be built being a provisional truss bridge built in wood by order of the German military. This bridge was opened in July 1942. The wood was not waterproofed, which meant that the bridge gradually decayed and had to be closed. A new bridge made of steel was opened in 1954. In 1977 the bridge was equipped with a separate path for pedestrians and cyclists. Today the bridge still stands on the same foundations from 1864.
There are plans for building a new bridge called Nydalsbrua in 2017, being placed just downstream of Sluppenbrua. The new bridge is planned to have four lanes. The plan is to make the new Nydalsbrua exclusively for cars, trucks etc., while Sluppenbrua is intended to be used only by pedestrians and cyclists.
River surfing.
Under Sluppenbrua lies the Sluppenbølgen (lit. "Sluppen Wave"), which is used for river surfing on surfboards or kayaks. The wave is said to work well for these purposes when the flow rate is around 140 cubic meters per second. Such a high flow rate is usually only seen when the snow melts during the spring, or when there is heavy rain, but also depends on how much water that is released from the power plants Øvre and Nedre Leirfoss kraftverk. Otherwise, it can be challenging to surf without holding a rope. The Sluppen wave is the only well known surfing spot in close proximity to Trondheim, but on days with heavy winds it is sometimes also possible to surf in the Trondheim Fjord.
The repair work of the Sluppen Bridge has affected the Sluppen Wave, and in 2018 the Trondheim Sports Council entered dialogue with the Public Roads Administration.