As stewards of public infrastructure, highway agencies have a fiduciary duty to regularly assess and update their facility preservation funding needs. Given the non-uniform nature of bridge construction activity over the decades, future years will be characterized by intensive preservation activity at certain years and relatively little activity at others. Such year-to-year fluctuations in bridge needs cannot be reliably identified using projections based on historical spending. Also, the historical spending-based approach for needs assessment suffers from issues such as temporal changes in inventory size or existing performance standards, difficulty of accounting for the effect of new performance measures on funding needs, and influence from other considerations besides engineering need. Furthermore, because bridges differ by material type, age and deterioration pattern, some years may indicate relatively higher funding needs than others. As such, the averaging effect of projections on the basis of historical spending may not provide adequate detail about how much is really needed on a year-by-year basis. The age-based needs assessment approach addresses only few of these problems. This paper presents a performance-based approach for long-term bridge network preservation needs assessment in a manner that overcomes the limitations of the historical spending and age based approaches. The performance-based approach utilizes parameters of individual bridge functional and structural features, deterioration rates, costs and service lives of preservation treatments, and performance-based thresholds. The results show that over the 2005-2015 analysis period, 25% of Indiana's state highway bridges need to be preserved at an estimated cost of $882 million. 345 bridges will need bridge replacement at a cost of $449 million, and 935 bridges will need rehabilitation at a cost of $433 million. Monetary amounts are in Year 2002 constant dollar.
Samenvatting