Bridges

A common problem among bridge owners/managers is the need to reduce spending whilst attempting to operate and maintain an increasingly ageing bridge stock. In response to this challenge the past decade has seen increased interest by European bridge owners and managers in the use of probabilistic methods for the assessment/management of their bridges and by the European Union in funding research in this field. Employed once a deterministic assessment of a structure has rendered a repair/rehabilitate/replace now scenario, the methods have been demonstrated to provide significant cost savings where the required safety of the structure can be demonstrated by probabilistic methods.

This paper presents a number of case studies where probabilistic methods have been employed to validate the safety of structures, which had received a repair/rehabilitate/replace now result following deterministic assessment. The cases are selected predominantly from Danish experience, as it is the Danish Roads Directorate (DRD), which leads the way amongst European agencies in the use of probabilistic methods as an assessment and management tool. This fact is evidenced by their publication in 2004 of a formal guideline for probability-based assessment of highway structures. Examples of probability based maintenance management strategies for structures are also presented.

The principle behind the approach is optimization of repairs whilst maintaining the required safety of the structure. The resultant cost savings are presented as justification in real terms for the adoption of these methods by bridge owners/managers in the management of their bridge stocks.