The collapse of the Laufenburg Bridge was not caused by a flood or a structural flaw in the concrete, but by an error in altitude measurements. The 225-meter-long, 11.2-meter-wide bridge was designed with two sections meant to align perfectly at the same height. However, they ended up being offset by 54 centimeters. This mistake happened because a correction was applied on the wrong side, doubling the natural gap instead of closing it. The issue stemmed from a difference in how Switzerland and Germany measure altitude at the Laufenburg site, which results in a 27 cm discrepancy. Switzerland measures elevation from the Mediterranean Sea, using a reference point known as the Pierre du Niton in Geneva. Germany, on the other hand, uses a system based on the level of water in Amsterdam. This difference had been known to the bridge's designers, who accounted for it in their calculations 12 years before the error was discovered. Construction took place in 2003 and 2004. The mistake occurred when the adjustment was made in the wrong direction, leading to the 54 cm offset. A routine check in December 2003 revealed the issue, and the project manager, Beat von Arx, admitted the error was on the Swiss side, though he initially didn't understand why. The canton of Aargau later clarified that the difference between the two altitude references had been misinterpreted during the project and corrected on the wrong side. At the time of the error, the support for the third stage of the bridge was being assembled, but the structure was not yet completed. The 54 cm offset was a small fraction—0.24%—of the bridge's total length. The canton of Aargau considered the correction feasible with minimal effort and no impact on the construction schedule. While the exact cost of the correction remains unclear, it is believed that the Swiss engineering firm's insurance would have covered the expense. The canton also stated that no additional costs were expected for the project owner. The bridge officially opened on December 17, 2004, a year after the error was discovered. The story of the 54 cm gap gained attention beyond engineering circles. Der Spiegel had covered the issue as early as January 14, 2004, calculating the discrepancy by adding 27 cm twice. The error became a topic of satire at the German carnival, and the inauguration did not ignore it. A man even shortened a fruit-picking ladder by 54 cm and gave it to the Swiss mayor of Laufenburg as a symbolic gesture to cross the gap. Despite proposals for new names like "Bridge of Difference" or "Bridge of 54," the structure retained its name, Hochrheinbrücke. On the 20th anniversary of the bridge's opening in December 2024, the Südkurier revisited the story. The bridge, located about 1 km upstream from the old Laufenburg Bridge, replaced a historic connection that had been in use since 1207. It now links the German road L 151a to the main road 7 in Switzerland, addressing the growing traffic needs of the area.