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The tensile forces acting on the cable of long-span bridges are one of the most important factors since they reflect not only the structural stability of cables but also the overall quality of construction. Currently, indirect measurement using accelerometers attached to the surface of the cable is widely used to measure the natural frequency of cable. The frequency obtained from the accelerometer is converted to the tensile force of the cable. However, it sometimes requires many hazardous labors such as attaching the device on the surface of cable and wiring it with data logger, which could hinder the safety of workers during the erection of cables. In this study, a method using laser vibrometer is introduced to measure the tensile forces on cables at a distance. In addition, this study developed a unique postanalysis computer program that can calculate the tensile forces in real time. Compared with the values obtained from the accelerometers, the laser vibrometer system provided accurate and reliable matching.

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<p>Currently, indirect measurement using dynamic data from cable is widely used measuring the natural frequency of cable from the accelerometer attached to the surface and convert the data into tensile force. However, it sometimes requires many hazardous works such as attaching the device on the surface of cable, writing it with data logger, etc, which could hinder the safety of workers in the middle of cable.</p><p>New measurement system(laser vibrometer tension measuring system, LVTMS) using wireless laser-vibrometer is developed to eliminate the unsafe works and adjust the cable tension force as well. Through the LVTMS, field engineers are able to figure out the cable tension force in no time while standing on the field. In addition, the result by the previous method is to be compared. As a result, the LVTMS is proved to be accurate and reliable</p>

The need for Light Rail Transit (LRT) in Korea has substantially increased as a result of the heavy traffic congestion in large cities such as Seoul. In Korea, most of the LRT construction projects have been achieved with the help of private sector investment, and the private sector companies that wished to participate in such projects had to make a rapid decision regarding their participation by conducting a thorough economic analysis before the beginning of the project. In other words, to ensure the success of the project, would-be participants had to estimate the precise amount of certain Life Cycle Costs (LCC), such as initial investment costs (construction cost) and maintenance costs. Experience, historical data, and know-how regarding previous LRT construction projects were needed to estimate the LCC of the project, but the private sector in Korea lacks the historical data and proper systems to support such decision-making.In this research, a life cycle costing system for the LRT construction project was developed to support feasibility studies on such projects. Construction cost was determined by the type of structure, its scale, and the methods of construction, so the 77 factors related to the construction cost had to be defined in advance, and a database that included related historical data also had to be built. In this project, the main factors that influence structures such as bridges and tunnels are defined, and a database related to unit costs is built based on the existing studies and databases. The LCC analysis process and the LCC model of LRT are defined through a study of existing research. An algorithm for the LCC analysis of LRT was made through a study on the analysis of uncertainty factors and cost breakdown structures that are adaptable to LRT. The developed system, which analyzes the construction cost and LCC cash flow, can considerably improve the efficiency of LRT LCC analysis.