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PROCEEDINGS OF THE TENTH INTERNATIONAL CONFERENCE ON CIVIL, STRUCTURAL AND ENVIRONMENTAL ENGINEERING COMPUTING
Edited by: B.H.V. Topping
An Automated Visual-Aid System for Inspecting Concrete Bridges
N.J. Yau and H.K. Liao
Institute of Construction Engineering and Management, National Central University, Taiwan, R.O.C.
N.J. Yau, H.K. Liao, "An Automated Visual-Aid System for Inspecting Concrete Bridges", in B.H.V. Topping, (Editor), "Proceedings of the Tenth International Conference on Civil, Structural and Environmental Engineering Computing", Civil-Comp Press, Stirlingshire, UK, Paper 15, 2005. doi:10.4203/ccp.81.15
Keywords: bridge management system, bridge inspection.
There are many bridges and tunnels in the transportation networks of Taiwan because of the mountainous aspect of the island. In 1999, the Center for Bridge Engineering Research (CBER) at the Civil Engineering Department of National Central University, sponsored by the Ministry of Transportation and Communication, established a bridge management system (Taiwan Bridge Management System, T-BMS) for bridge management agencies. Currently, there are over 25 thousand bridges in the T-BMS database. Since many of these bridges were seriously damaged or destroyed before reaching their service lives as a result of human or natural factors, bridge inspection has become an important task for the maintenance of these bridges.
The methodology of bridge inspection and evaluation used by T-BMS is called DER&U, which was initiated by a joint effort of two consulting companies. In the DER&U methodology, "D" stands for degree of deterioration; "E" represents extent of the deterioration; "R" implies relevancy to safety of the deterioration; and "U" depicts urgency for repairing of the deterioration. All of these indices are numerically rated on an integer scale from 1 to 4; a smaller digit means less important, or little degree, of deterioration of an inspected component of the bridge.
In the DER&U, twenty-one components are identified for inspection of a bridge; they are: (1) approaching embankment, (2) approaching guardrail, (3) waterway, (4) protection works for approaching embankment, (5) abutment foundations, (6) abutments, (7) retaining walls, (8) pavements, (9) superstructure drainage, (10) sidewalks, (11) guardrails, (12) scouring protection piers, (13) pier foundations, (14) piers & columns, (15) bearings, (16) earthquake brakes, (17) longitudinal girders, (18) transversal beams, (19) decks & slabs, (20) expansion joints, and (21) others. After each of the twenty-one components of a bridge is inspected and rated, a formula is then incorporated to calculate the overall condition of the bridge.
The inspection of bridges is performed by trained inspectors with the naked eye and hand-carried tools. There are problems in current bridge inspection processes. Firstly, such inspection may result in various ratings due to various levels of knowledge, training, and experience of the inspectors. Secondly, most bridge management agencies often face problems in personnel turnover, which results in a lack of training and experience of the inspectors. A third problem is the inputting of the inspection data into T-BMS. When inspectors go to the bridge sites they record inspection results on papers and key in those data into T-BMS after coming back to their offices. Mistakes are sometimes made in this process in addition to the required labour time. Thus, to solve the above problems, an Automated Visual-Aids System (AVAS) is developed in a tablet personal computer.
The AVAS is designed to assist the inspector in evaluating bridge damage with better consistency and in keying in the inspection data with better efficiency and accuracy. Before going out to a bridge site, an inspector can download, from the T-BMS bridge inventory to the AVAS, the basic data and historical inspection records of the bridge that is to be inspected. The AVAS is able to generate a bridge inspection table automatically based on the geometrical attributes of the bridge. In addition, the AVAS has a database which consists of 279 photographs showing various degrees of deterioration of bridge components, and each of the photographs has a deterioration rating and a suggested repairing method attached. The pre-determined ratings and repairing methods are determined by bridge inspection experts.
At the bridge site, the inspector selects a bridge component from the AVAS generated inspection table and then AVAS will display deterioration photographs of such component from its database. Accordingly, the inspector can compare and choose from the displayed pictures a photograph which matches most the deterioration conditions of the bridge component. After the photograph of deterioration (D rating) is selected, the inspector, again, selects from a set of simplified drawings to aid the determination of the extent of deterioration (E rating), and a predefined equation will be incorporated to calculate the relevancy (R rating) and urgency (U rating) of the inspected bridge components. Consequently, after all the twenty-one components of the bridge are inspected, a click on an "update" bottom in AVAS will automatically transmit the inspection data to the T-BMS database when the two systems are connected.
The AVAS system developed, was field tested by Chung-Li Section of the Directorate General of Highways. Successful and satisfactory results have been obtained. The AVAS is planned to be extensively experimented in many of the bridge management agencies in the near future.
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