A Discussion on the Efficiency of NBI Translator Algorithm

The National Bridge Inventory (NBI) database is an extensive source of information on highway bridges in the United States. Among more than 100 NBI elements—deck, superstructure, substructure, and culverts—condition ratings are of special interest for bridge engineers and managers. The data for these condition ratings come from biannual bridge inspections in the field. As a part of their bridge management programs, many states have been collecting element-level condition data (mostly Pontis inspections) for more than 15 years. Element-level data provide more detailed condition data on subelements of the aforementioned general NBI element categories. Due to having such detailed condition data at hand, there has been an interest in developing algorithms that have the capability of estimating the NBI condition ratings from the Pontis element inspection data. If a sound estimation tool could be developed, the biannual NBI inspections done for these condition ratings would be deemed unnecessary. The NBI Translator is one of the algorithms that have been developed to achieve that goal and also works as a built in module within Pontis. Recently, there has been some concern on the degree of accuracy of this algorithm by users of both Pontis and the translator. This paper presents a literature review on bridge management systems and bridge inspections in the United States. In addition, background on NBI Translator algorithm and discussions on the efficiency of the tool are provided. A comparison study between the generated and actual values of the NBI ratings for the bridges in Iowa is also included. The paper concludes with a discussion on how to improve the algorithm and use the translated results in a simplified network-level tool for bridge management decision making