Christoph Klauser, what is the service life expectancy of a bridge?
The service life is generally about 80 to 100 years. Many of the bridges we have in Europe today were built after the Second World War and are thus gradually nearing the end of their service lives.
What is the greatest challenge facing bridges?
Thomas Wuhrmann: Just like other structures, bridges are subject to a variety of influencing factors that can lead to wear and structural changes over time. Continually growing traffic volumes are, without a doubt, one of the greatest challenges. Bridges today suffer increased stress within short periods of time due to the volume of traffic and, most importantly, heavy vehicles using them. Many of today’s bridges were simply not designed for this enormous load when they were constructed. Added to this are environmental factors, such as wind and temperature, that a bridge is also exposed to over time.
A multitude of factors indeed, so how exactly are bridges monitored?
Christoph Klauser: Bridges are civil engineering structures, and these are governed by standards that define the inspections and checks the structures must undergo at particular intervals. Highway operators, such as ASTRA in Switzerland or Autobahn GmbH in Germany, are responsible for implementing these and commission specialized engineering consultants with the realization. Manual inspections and checks determine what condition the bridge is in. However, reliable data is needed to calculate the effective condition of and strain on a bridge with the models employed.