MANAGING BRIDGE MAINTENANCE

The objective of a bridge manager is to minimise the expenditure on maintenance work subject to keeping the stock in a safe and serviceable condition. Maintenance work can include preventative treatments, repair, refurbishment and the replacement of elements. Traditionally preventative maintenance has been favoured since it is relatively effective and easy to carry out. Nevertheless since existing bridges are in a wide range of conditions all types of method must be considered. The manager has to decide when maintenance should be done and which method to use in order to achieve the objective. To make this decision the manager needs information about the expected rate of deterioration that will occur following a range of maintenance treatments, including the 'do nothing' option, and the full costs associated with carrying out each maintenance option. In addition the manager must decide for how long the bridge will be required and a minimum state beyond which the condition of each element should not fall. The paper describes some features of a management system that has been developed as computemodules designed to help the manager achieve his objectives. These are: (a) a discrete system of condition states for assessing the condition of bridge elements; (b) predicting condition states in the future using deterioration rates; and (c) optimising maintenance costs subject to a minimum allowed condition constraint. The cost and condition implications of departures from the optimal maintenance programme can be used to: (i) assess the benefits of deferring or advancing maintenance work on particular bridges in order to coordinate maintenance on a section of road; and (ii) prioritise maintenance when the budget is insufficient to carry out the optimal programme. For the covering abstract see ITRD E111699.