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Abstrakt

Experience gained from timber structures other than bridges shows that they can last for many hundreds of years. But experience also shows that timber structures may only last for a very few years. It all depends on their design and protection. A case study of existing bridges carried out by two students in 2009 shows that the design of Norwegian timber bridges has not always been good enough, and in one case decay was in progress. On the basis of available data, the monitoring project indicates that a service life of more than 100 years can be expected.


This study of existing bridges also shows that it is not possible to rely on only one type of protection in order to obtain more that 100 years of service life. Both physical and chemical protection are always necessary. In a few cases, physical protection alone is sufficient. It seems likely that some design
mistakes will continue to be repeated, such as that of assuming that chemical treatment alone provides adequate protection.


The parts of the bridge that are most difficult to protect may be those that it is impossible to inspect, such as covered bridge ends.

Referanser

Monitoring of Timber Bridges in Norway, Fred Evans, Norsk Treteknisk Institutt


Inspeksjon av trebroer 2009, Rapport 2567 Norwegian Public Roads Administration



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