###The Laufenburg Bridge Math Error
Laufenburg, Germany and Switzerland, 2003 — An international bridge missed its center connection completely because a technician put a plus sign where a minus sign belonged.
In 2003, Germany and Switzerland agreed to build a brand-new, 225-meter concrete bridge across the Rhine River. Construction crews started on opposite riverbanks, working their way toward the dead center. There was just one geographical catch: the two nations measure sea level differently.
Germany bases its elevation on the North Sea, while Switzerland uses the Mediterranean Sea. This creates a known 27-centimeter difference. Engineers knew about the gap and specifically warned about it on the blueprints. But during construction, a Swiss technician accidentally added the 27 centimeters instead of subtracting it.
When the massive concrete spans finally reached the middle of the river, engineers realized the disaster. They didn't have to demolish the bridge, but they did have to frantically lower the entire German side and adjust the abutments to finally click the two pieces together.
The Laufenburg Bridge Math Error — Laufenburg, Germany and Switzerland, 2003