Effective and efficient conservation and improvement of a roadside living environment can be expected through the implementation of integrated measures for motor vehicles, their traffic flows, land uses along roads, road structure, and other relevant factors. This report focuses on the measures which have been adopted by the Japanese Government in the area of pavement technology to conserve and improve a roadside living environment. The environmental problems related to roads include traffic noises, traffic-induced vibrations, air pollution along roads and heat island phenomenon which is the temperature rise in urban areas caused by an increase in anthropogenic heat and reduction in green areas by road construction, etc. To cope with these problems, several types of pavements are newly developed as described below. - Porous elastic surface pavement molded from a mixture of urethane resin and rubber chips produced by cutting used tires has roadside traffic noise reduction effects which are about 12dB to 15dB greater than dense graded asphalt pavements in the case of passenger cars. - Vibration-reducing pavements has effects that vibration levels at roadway edges immediately after pavement construction can possibly be reduced by 2dB to 8dB by comparison with dense graded asphalt pavements. Researches are in progress on development of Air Pollution Cleaning Pavement involving the use of clean solar energy by installing titanium oxide on road surfaces with which air pollutants come into contact before their diffusion, near the source of NOx emission. Research work has been pursued to develop water retaining pavements which store moisture inside in order to lower temperature of their surface , and lessen their thermal radiation by reducing the heat stored in the pavements through its evaporation. Procurement methods for pavement works oriented toward environmental improvement are now introduced on trial basis to conserve and improve a roadside living environment. Pavements have been constructed based on recipe or method based specifications for many years in Japan. In April 2001, the Road Structure Ordinance in Japan was revised to incorporate the results of pavement technology development into the Ordinance, enhance road user benefits, and reduce user costs by promoting technological innovations in pavements, while adopting performance-based specification . For the covering abstract see ITRD E135448.
Abstract