In total, the Ludwig Canal was led over rivers, roads and cuttings ten times on trough bridges, so-called bridge canals (today: canal bridges). Originally, 13 bridge canals were planned, but the three largest were replaced by high earth dams for cost reasons. Today, the two bridge canals, which are not far from each other, over the Schwarzach (17.50 meters high, 14.60 meter span, 90 meters long) and the Gauchsbach (8.50 meters high, 11.60 meter span, 42.50 meters long) have been preserved. A trough bridge, the Oberndorf Aqueduct,[13] spans the connecting road from Gösselthal to Oberndorf (Beilngries) (♁49° 3′ 19.2″ N, 11° 28′ 2.4″ E), although the canal no longer carries water there.
The Schwarzach Bridge Canal, which carries the canal over the river at km 95.2 between locks 59 and 60 (♁49° 21′ 19″ N, 11° 12′ 20″ E) with a height of 17.50 meters, is considered the technical masterpiece of the project. The 90-meter-long construction made of sandstone blocks grouted with sandstone powder and lime spans the Schwarzach valley with an arch with a span of 14.60 meters. Architecturally, von Pechmann and later the royal building councilor Leo von Klenze based their plans on Roman aqueducts. However, this bridge canal also caused the project's biggest setback when it had already been completed in 1841 and had to be almost completely demolished in 1844 after several attempts at repair.
Source: Wikipedia