The discussion of the need of an annual main inspection of protected timber bridges

Building with wood is future-oriented and indispensable with regard to Germany's climate policy objectives, However, bridges are rarely built in timber in Germany, as they are generally suspected of not being durable due to some poorly planned examples. Therefore, the federal government requires an annual main inspection in its regulations for almost all timber bridges which is a big competitive disadvantage compared to bridges made of other building materials, where main inspections are only required every 6 years. In order to counteract the loss of image in timber bridge construction, long-term measurements of timber moisture content were carried out on nine protected timber bridges in Germany in the research project Protected Timber Bridges (ProTimB). Over a period of 2.5-6 years, the development of timber moisture content was monitored on nine protected timber bridges of different construction types with different ambient climate conditions. The aim of the monitoring was to demonstrate the effectiveness of structural wood protection and to investigate the influence of close distance to waters and exposition to spray due to traffic on the development of the timber moisture content. This paper summarises the main results of the monitoring. Based on the findings, the need for an annual main inspection for protected timber bridges over waters is discussed.