Inspection techniques are not new in the world of the bridge management systems. Related
to structural safety and risk oriented together is more and more wanted, while the budget for maintenance is
growing. Till today it was quite common, that the inspection office contains two arts, the inspection part and
an additional analysis part of the structure. The inspection part was foreseen and the calculation part needs an
extra budget for the contractor. So a need was born to relate the inspection part to the calculation part based
on risk analysis in order to minimize the extra costs after the inspection part. A weighted method related to
the structural safety of the structure and the condition of the structure indicates a so-called risk index of the
structure.
The first possible difference between the design parameters of the structure and the actual use or the
wished use of the structure gives a first parameter of the weigthed method. A second difference is the hardening
behaviour of the concrete material in the structure. The concrete structures build before 1975 show a hardening
behaviour, where sometimes the concrete has twice the strength of the old design circumstances. This
means the structure can carry more load. The traffic load could be growing too, this item is an important negative
parameter for the structure.
Till now the scope is mentioned in a way that all parameters from the design period of the structure are
known. However during all the years some information can be destroyed or lost, this indicates a higher risk for
the safety of a structure because there are coming some uncertainties around the design parameters.
All together a weigthed method is developed to get a ranking of the structures for extra calculations of the
structure and the way of inspection of a structure.
This method can be explained and discussed in a paper on a wide range of concrete structures build in the
20th century.