Development of pavement to absorb an electric wave

Electric Toll Collection (ETC) has been spreading across Japan since December 2001. As ETC is a system which does short-range communication using 5.8GHz radio wave between roadside unit and on-board equipment, the leakage of radio waves cannot be avoided. The direct wave is indispensable to communicate, but the wave after reflected on the walls or the pavements needs to be eliminated so that ETC system can operate correctly. Although the radio wave absorption panels are equipped to restrain reflected waves, these panels cannot be applied to several types of tollgates because of structural limitations. In this situation, it is necessary that the pavement should have a function which restrains reflected radio waves. For these reasons, a radio wave absorption pavement with iron oxide dust, which is added during asphalt mixing was developed. Trials with the absorption pavement are described. For the covering abstract see ITRD E157233