Without its 27 locks, the 362 km long Neckar would be a fast-flowing river."The name Neckar is Celtic in origin, meaning fierce, wicked, fast river, and it is derived from the ureuropean word 'nik' which means to rush." (Wikipedia)
The Poppenweiler barrage is a river barrage and consists of a double lock on the left bank, a hydroelectric power station on the right bank and a three-field weir in the middle of the Neckar. This construction is typical of the 1950s.