Applications of GPS for Maritime Construction Work in Japan and Further Plans

摘要

RTK-GPS is most suitable for maritime construction work among all systems. The requirements of reference stations for maritime construction work are high-power radio waves, high-speed data transmission rate, and high reliability. Maritime GPS Promoting Solutions provides services that satisfy these requirements. The maximum service range of Maritime GPS Promoting Solutions is 10 -15 km from a reference station. That covers most of the maritime construction sites.GPS has been spread in all kinds of maritime construction work at present according to the enlarging scale of construction that requires high efficiency. There are some reasons why GPS is popular in maritime construction work in Japan. One of them is the necessity of high accuracy for specific construction work such as soil improvement work. The other reason is that common coordinate of GPS enables positioning with no relative error among many work vessels. Vertical positioning has been also introduced to measure ground level of reclamated land in construction work of offshore airports lately.RTK-GPS is now being introduced into the other areas. One of the most important approaches is GPS wave measuring buoy. It measures wave height by the motion of the buoy floating offshore with GPS. As GPS is able to measure the absolute height, it is able to detect long period waves including tsunami. It enables early escape from the hazard caused by tsunami. As GPS wave measuring buoy is desirable to be located as far from the coast as possible, the accuracy of vertical positioning, service area, and long-term durability and reliability of GPS devices on the buoy are critical factors. An experiment considering small boat as buoy is carried out using time-sharing method. The result shows excellent perspectives.