The system for providing traffic information in Tokyo makes use of television and radio media by the Japan Traffic Information Centre for offering macro information on a regular basis, while workers at the Traffic Control Centre provide for more detailed driver needs. In addition, the infrastructure for providing primarily micro information in real time includes such independently developed services as roadside communication, traffic information signs and automatic answering telephones and facsimile equipment. Furthermore, as a link in the UTMS (Universal Traffic Management System), AMIS (Advanced Mobile Information System) was introduced beginning in April 1996, making it possible for individual drivers to obtain the same level of information as that of the Traffic Control Centre through display of traffic jams, as well as regulations and their hours, on car navigation maps. Although among all these various methods of providing information the traffic sign is the best for its ability to transmit information to the largest number of people, including pedestrians, its information is limited by restrictions on the amount of information it can provide and its fixed position, so that it cannot always fulfil the needs of those who require the information. In addition, an information providing method is desirable to deal effectively and in a timely manner with the area, location and contents of noticeably changing traffic regulations during policing, events or natural disasters. To be able to deal with these situations, the Metropolitan Police Office introduced a movable traffic information device (Sign Car) in 1987, which permitted the provision of traffic information for such events as fireworks displays and marathons, in addition to ordinary safety information. Furthermore, they were put to work in Hyogo Prefecture at the time of the 1995 Great Hanshin Disaster to aid in the recovery there, making use of the merits of movability to provide information such as traffic regulations that changed from day to day, publishing evacuation sites and the state of restoration. As a result of the high marks these activities earned, they were adopted by the prefectures of Osaka, Chiba and Aichi to deal with similar situations. However, more than 10 years have now passed since the first introduction of the sign car, and their obvious depreciation and obsolescence is leading to their updating. Most noteworthy in this updating are the fact that the displays have become more detailed and are in full colour, and computer graphics have made it possible to deal with all kinds of input media, including images. Also, by making use of our experience in the operation of sign cars in the past, it has now become possible to send the latest information on present conditions and future regulation at the location, taken from the various sorts of information collected at the Traffic Control Centre, coupling the Traffic Control Centre and the sign cars through a mobile communications network. Furthermore, in regard to on-site demands from the Traffic Control Centre, the directive site can be displayed on the sign car car navigation system, an added function to aid mobility. And at the Traffic Control Centre, a grasp of conditions at the site to which a sign car has been dispatched can be confirmed by pictures, taken by video camera.
Abstract