Assessing the safety and serviceability of existing highway structures

Although considerable effort has been put into the development of new standards and codes for the design of new structures, comparatively little has been done on the development of documents for the assessment of existing structures. The results are discussed in a European action that addresses that imbalance. The action, known as COST 345, "Procedures Required for Assessing Highway Structures," is supported by the European Commission's COST program (COoperation in Science and Technology) and involves experts from 16 countries. The purpose is to identify the procedures and documentation required to inspect and assess the condition of structures such as bridges, culverts, earth-retaining walls, and tunnels. The action also defines the requirements for future research work, provides information on the stock of highway structures (this can be used as input to budgetary plans for maintenance works and operating cost models and also for establishing recommendations for construction options), and identifies those structures not amenable to simple numerical analysis. In particular, the focus is on the work carried out by Working Groups 4 and 5 within the COST 345 action on procedures and numerical methods for assessing the safety and serviceability of highway structures. These working groups cover issues such as overall assessment procedures and levels of assessment, uncertainty modeling (load, material, and structural response modeling), and reliability analysis and target reliability levels.