Many countries around the world are currently facing increasing demands on their resources for the maintenance of their existing bridges. Many of these bridges were built long ago and are inadequate for modern traffic requirements while others are showing serious deterioration resulting from the application of de-icing salts and from other adverse factors. Faced with limited resources, the authorities are having to prioritise the work. It is now generally accepted that the only rational way to prioritise is to determine the inherent risk levels in the bridges so that those at most risk can be dealt with first.

The report is not intended to be a detailed technical manual which will by itself enable the use of the reliability method. It describes the broad principles of the method, its benefits, potential areas of application and some practical examples of past use.