The Danube River and Canal (in Vienna) has been, and continues to be, a major navigation route in Europe. The word "canal" is slightly misleading here, as the flume is actually rapidly flowing, deep, and full of water. It is commonly known to the Viennese as the "Viennese arm." Urban development in the 19th century imposed regulation of the river arm and a new bed was built with rock side slopes and high quay walls. In the 20th century, tracks for the city train and modern traffic routes were laid alongside the canal banks. The canal now acts as a popular relaxation spot for local Viennese, especially in the summertime.