###### Abstract  
This paper proposes a method for monitoring the structural health of concrete bridges in Iran. In this method, the bridge condition index (BCI) of bridges is determined by the analytical hierarchy process (AHP). BCI constitutes eight indices that are scored based on the experts' views, including structural, hydrology and climate, safety, load impact, geotechnical and seismicity, strategic importance, facilities, and traffic and pavement. Experts' views were analyzed by Expert Choice software, and the relative importance (weight) of all eight indices were determined using AHP. Moreover, the scores of indices for various conditions were extracted from experts' standpoints. BCI defines as the sum of weighted scores of indices. Bridge inspectors can examine the bridge, determine the scores of indices, and compute BCI. Higher values of BCI indicate better conditions. Therefore, bridges with lower BCI take priority in maintenance activities. As the case studies, the authors selected five bridges in Iran. Successful implementation of the proposed method for these case studies verified that this method can be applied as an easy-to-use optimization tool in health monitoring and prioritizing programs. transportation infrastructure; concrete bridges; structural health monitoring; bridge condition index; analytical hierarchy process; mobility; multiple-criteria decision analysis; decision making; civil engineering; infrastructure +
Footnote †: journal: Medical  
bridge maintenance, including repairs or reinforcement, is the cornerstone of the BMS [8, 11]. Traditionally, for small-sized bridges, the prioritization of bridge maintenance projects was carried out based on engineer's assessments. In large and old bridge networks, it was conducted in accordance with concepts and principles of optimization in project budget allocation. Today, the bridge condition index (BCI) is used for this purpose. BCI is a good benchmark for prioritizing BMS [12]. The service life of a bridge is divided into four different phases [13]:  
* Design and construction;
* Start of damages (early damage stages);
* The spread of damages;
* The expansion of damages. Under the famous Law of Five, each dollar spent on the first phase will equal $5 in the second phase, $25 in the third phase, and $125 in the fourth phase [13]. According to this law, any miscalculated decisions about maintenance, repair, and rehabilitation (MR&R) in bridges would incur surplus costs. With this in mind, there is a need for a decision support system (DSS). DDS aims at improving the bridge network condition and allocating the budget appropriately [14]. Most of BMSs are founded upon processes that optimize the cost of a lifecycle. They tend to overlook factors such as environmental impacts and social impacts. This gives rise to a number of problems, especially when the existing financial resources are higher or lower than the cost of the computational life cycle [15]. In this paper, the main goal is to present an applicable method for determining the condition index of the concrete bridges in Iran. For this purpose, firstly, eight critical indices were selected. These indices include structure, hydrology and climate, safety, load impact, geotechnical and seismicity, strategic importance, facilities, and traffic and pavement. Each index comprises a number of sub-indices. Next, the authors developed a questionnaire for surveying the views of experts. The questionnaire was about the relative importance of the indices and sub-indices. Moreover, examining various conditions of sub-indexes is another aim of this questionnaire. After that, this questionnaire was distributed among bridge experts. Then, experts' feedbacks about the relative importance of indices and some sub-indexes were analyzed by Expert Choice software. This software resulted in the relative weight of these indexes and sub-indexes using the analytical hierarchy process (AHP). For all sub-indexes, experts' views about conditions scores were gathered as well.