Risk-based life-cycle analysis of highway bridge networks under budget constraints

Abstract

This paper describes the life-cycle analysis of the risk to highway bridge networks subjected to overweight traffic loads under maintenance budget constraints. The risk to the network is initially evaluated based on the current condition of its constituent bridges and then the life-cycle analysis is performed to identify the level of risk reduction that is possible given a particular budget allocation. The deterioration rate is extracted from National Bridge Inventory data. The risk is monitored as the deterioration of bridges progresses over the years. Bridges are ranked in descending order starting from the bridge whose failure has the highest impact on network risk. Maintenance is scheduled sequentially on the riskiest bridges until the entire budget allocation is depleted. The methodology is illustrated using as an example the highway network of major interstate and state roads in New York State. The paper compares the results of the proposed life-cycle risk analysis for several budget levels. The results show that network risk can be reduced from its present level by 20% if current expenditure rates are maintained. Risk reduction can reach 37% if the budget for bridge rehabilitation is increased to match that recommended in the ASCE report card for America’s infrastructure.