Conversion of legacy inspection data to Bridge Condition Index (BCI) to establish baseline deterioration condition history for predictive maintenance models

Bridge Management Systems (BMS) have been introduced across the world with the goal of aiding the decisions regarding maintenance, rehabilitation and replacement (MR&R) of bridges. Deterioration modelling is the most important part of the BMS because the ability to predict the future condition is vital as it will determine the quality of the decisions made. Markovian-based models are the most common predictive maintenance tool utilised in existing BMS, by obtaining probabilities of transition of bridge condition from one state to another based on historic bridge inspection data. Prior to the introduction of the Bridge Condition Index (BCI) the use of the numerical, 1-4 or similar, condition scoring led to inaccuracy in deterioration models because the condition ratings are only subdivided into 4 categories with wide range and uncertainty on the exact boundary of each category. The BCI has been introduced to facilitate a uniform national assessment method which is less subjective. Ultimately BCI will facilitate significant improvement in the predictions of future bridge deterioration. However, in the short term the lack of consistency between the methods means condition deterioration is no longer directly comparable over long periods of time leading to uncertainty in the true condition of many bridges across strategic road networks. This paper details the conversion of approximately 17 years of “Legacy” inspection records to BCI values for 6978 bridges across the Northern Ireland (NI) road network.