Bridge owners who have to manage their bridge stock are concerned with bridge deficiencies. The main concerns are the degradation of bridge elements due to ageing, accident, and other factors. This is evaluated by the bridge condition index.

But bridge owners also have to manage the evolution in the characteristics of the bridge: the original design may no longer be appropriate (number of lanes, load capacity, flooding frequencies, standards and other characteristics). In this case there is a need for increasing the bridge service level.

All those elements require bridge rehabilitation (repair or construction of a new bridge).

Considering all those bridge needs, the bridge owner will have to decide at a certain moment for each bridge what to do:            

•  maintain the bridge in its current condition (if safety is guaranteed) with low impact on the traffic or other functionalities;
• perform minor rehabilitation with a low influence on the bridge life time;
• carry out a major rehabilitation with a substantial extension of the bridge life time;
• reconstruct a new bridge.

The way to compare different solutions is important and the main goal of this report.

A questionnaire on that subject was widely distributed and answers were received from 17 countries. Based on those answers it has been possible to make a review of best practices and to propose a comparison process for rehabilitation considering technical and economical aspects. This process includes a life cycle cost analysis (LCC). It will be explained in this report including the uncertainties related to this LCC, especially the value of the discount rate, the effectiveness of the maintenance program during all the remaining bridge life time and the analysis duration. Examples will be provided to illustrate this LCC analysis.

This comparison process is also included in a global rehabilitation process for bridge stock. Indeed, even if was not the main part of the issue, considering the answers received, it was decided to include also a prioritization phase of all the needs in bridge rehabilitation.