 Qiao Weiyue also built five double slipways (lit. dams) between Anbei and Huaishi (or, the quays on the Huai waterfront). Each of these had ten lanes for the barges to go up and down. Their cargoes of imperial tax-grain were heavy, and as they were passing over they often came to grief and were damaged or wrecked, with loss of the grain and peculation by a cabal of the workers in league with local bandits hidden nearby. Qiao Weiyue therefore first ordered the construction of two gates at the third dam along the West River (near Huaiyin). The distance between the two gates was rather more than 50 paces (250 ft) and the whole space was covered over with a great roof like a shed. The gates were 'hanging gates'; (when they were closed) the water accumulated like a tide until the required level was reached, and then when the time came it was allowed to flow out. He also built a horizontal bridge to protect their foundations. After this was done (to all the double slipways) the previous corruption was completely eliminated, and the passage of the boats went on without the slightest impediment.
