Estimating Asset Deterioration and Life Expectancy by Using Levels of Service

As agencies have implemented maintenance quality assurance processes over the past 10 to 15 years, the agencies have also begun to amass valuable databases of condition and performance data, often expressed in terms of levels of service. These databases address a wide range of asset types, especially roadway and roadside features such as signs, pavement markings, traffic signals, lighting, culverts, sidewalks, and curbs. At the same time, element and condition state data have been gathered by most of the state departments of transportation for bridges and often for structures other than bridges. A few agencies have taken the next step in developing deterioration models to forecast changes in structure condition, either in the absence of maintenance activity or in response to specific agency actions or policies. The state of the practice in bridge deterioration modeling is a matter of active research but is increasingly becoming repeatable and relevant to asset management decision making. Moreover, some examples of bridge inspection and deterioration models already address a variety of nonbridge structures and a variety of performance concerns beyond physical deterioration. This study connects the level-of-service approach now frequently used in maintenance management with the quantitative forecasting of deterioration frequently used in bridge management. The result is a framework for prediction of levels of service and life expectancy that can be useful for management of all types of transportation assets.