In Japan, road improvement was mainly implemented after World War II. Especially, improvement was rapidly implemented through the 1960s to 1970s. Correspondingly, it is expected that, at the early stage of the 21st century, these road stocks will rapidly deteriorate, and therefore there will come the age for full-scale maintenance. So, the situation now demands us to maintain, repair and update these road systems without missing proper time, so that we appropriately hand next generation such road stocks as a heritage. Also, it is one of the characteristics of roads in Japan after the Second World War that sizes of vehicles have become larger. In 1993, the restriction on the maximum gross weight of a vehicle was relaxed from 20 tons to 25 tons, and in 1994, it was announced that trailer transportation where each trailer truck carries full of overseas containers of international standard will become possible as one of the Policy to Relax Restriction Plan which was established in that year. And currently, reinforced concrete piers of road bridges throughout the country are being retrofitted to have them more resistance for earthquake, taking Hanshin Earthquake Disaster an opportunity. This is the same effort as what we see in the United States of America, where reinforcement of piers for earthquake-resistance, which they have been studying in full-scale since 1980s, has been implemented since Loma Prieta Earthquake. Management of "road space" has become important theme, too. In Japan, most of lifelines of utilities such as electric power, gas, telephone, water and sewer are conventionally accommodated in under-road (underground) space in urban areas. Therefore, to carry out a work to replace deteriorated lifelines with new ones or to connect lifelines to buildings or apartments newly built along a road, we have to excavate a road surface ,which causes traffic jams as a serious social problem. In 1962, the Common Duct Law was established to newly install common ducts in orderly and projected manner so as to completely eliminate lifeline works on a road by accommodating lifelines and other systems in such ducts. In areas where common ducts were well installed, lifelines survived the disaster with almost no damages ,while a lot of them were seriously damaged by Great Hanshin Earthquake. Consequently, earthquake-resistance of a common duct was highly recognized. In addition, so called "multi-media" communication society is rapidly developing in Japan, demanding large volume of information transmission service for companies' use as well as individuals' use. In order to match this demand ,it is required that we utilize under-road as a space-network to accommodate the infrastructure for such highly sophisticated information society, as well as to widen space of a sidewalk by removing obstacles on a road such as an electric or telephone pole ,as a part of road-space-management. As such, the issue of using road space effectively has become one of important tasks to be achieved, and to respond the task, projects to install various underground-accommodation-space networks are now about to start under strong leadership by the Minister of Construction. (A)
Samenvatting