# Knowledge-Based Fuzzy Expert System to the Condition Assessment of Historic Road Bridges
### Assessment of Bridge Condition  
The assessment of the bridge condition is based on data from periodic field inspections of bridges. The purpose of the condition assessment is to assess the degree and extent of deterioration and deficiencies. The bridge is divided into elements or components, and the condition of each element or component is expressed using a condition assessment. Condition estimates are defined by numerical or linguistic variables as measures of the degree and extent of deterioration. The condition is assessed through an inspection process that involves the use of specific techniques to assess the physical condition of the bridge. A detailed visual inspection is carried out on a routine or planned basis to detect serious deficiencies and assess the degree of deterioration of the bridge elements. Additionally, ad hoc inspections should be carried out after natural disasters such as earthquakes and emergency inspections after accidents due to specific failures. If serious damage is found during the visual inspection, a detailed test using non-destructive testing (NDT) methods is needed to determine the extent of damage to the bridge element. It is also necessary to inspect the condition of the bridge after the maintenance, refurbishment or repair work to ensure that damage or malfunction has been rectified, after which routine inspections and maintenance should continue to be performed on the bridge [12]. The bridge inspection system controls the entire bridge life cycle process and provides the information needed for a decision-making system that is responsible for all activities during the life of the bridge, such as routine maintenance and repair, upgrading and replacement. [PERSON] and [PERSON] [13] state that the usual bridge inspection process involves four levels:  
1. routine checks to confirm the general safety and usability of the structure for road users;
2. a comprehensive visual inspection carried out by a qualified expert to assess the condition of each bridge;
3. detailed inspections carried out when further tests during level 2 are required and carried out by qualified engineers;
4. load assessment due to changes in dynamic load, i.e., due to the application of new types of vehicles or due to the need to confirm the structural capacity of bridges. As a result, the responsibility of managers in charge of bridge reconstruction is crucial to make transparent decisions with the lowest projected losses [14]. Most decisions related to bridge maintenance are made based on assessments based on visual inspections performed by trained engineers whose task is to see, identify, and record phenomena relevant to assessing the condition of bridge construction and equipment, or indications leading to damage. Visual inspection, along with all other test methods, is considered to be the most important means of assessing the condition of a bridge. How high quality and accurate the visual inspection will depend on the training and equipment of the experts conducting the inspection. The effectiveness of management in maintenance and renovation planning significantly depends on the uniformity of the results of the visual inspection, i.e., on the assessment of the type of damage [9]. After the visual inspection, assessments of the condition of the element are assigned, and are further incorporated into a unique assessment of the entire building [2]. Assessing the condition of structures can be defined as a process that determines how reliably a structure can take on current and future actions, while fulfilling the task of its existence in the planned time of use. Simple methods (such as reviewing documentation) are most commonly used for lower levels of assessment, while for higher levels of assessment it is necessary to reduce uncertainties by inspecting the structure and testing the material. As an option, wherever possible, it is better to choose non-destructive testing methods [15].