Bridges are designed with a limited service lifetime. For new constructions, this can be up to 100 years. Often the forecast design lifetime is re-evaluated if visible damage is detected within the structure, such as cracking as a result of increased traffic loading, corrosion, or as a result of environmental erosion.
The Gänstor Bridge connects the cities of Ulm and Neu-Ulm in Southern Germany. Constructed in 1950, the 96 m long bridge is nearly 70 years old and not so far off its design service lifetime of 80 years. Upon a recent inspection by the city of Ulm, pre-stressed concrete reinforcements inside the bridge indicated several locations of corrosion and rust build-up. Left unmaintained, these effects will eat away at the bridge’s load-bearing members, further compromising the structural integrity and accelerating the reduction of the serviceable lifetime. Investigations indicated that the corrosion damage already inflicted on the Gänstor Bridge is irreparable and as such, the bridge will be inevitably be overhauled in the coming years, shortening its forecast design service lifetime.