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＜Site policy and condition of use＞

 This website was produced based on the results of the research project by the International Association of Traffic and Safety Sciences (IATSS), with the aim of informing the general public on the status of roundabouts in Japan.
 Anyone is free to use the information published on this site, but please state the source when using it. An example of citation is as follows.
ex)：
Research project of the International Association of Traffic and Safety Sciences (IATSS), "Providing information on the actual situation and case studies of roundabouts in Japan based on the database development"(URL of the relevant page) (accessed on 0/0/00)
 The information on this site is carefully prepared and updated as needed, but may not always be the most up-to-date. In addition, the accuracy and completeness of the information is not guaranteed.
 The website provider shall not be liable to the users for any damages arising from the use of this website, or from the writing of data by other party, unauthorized access, etc.
＜How to use＞
Map： The location of roundabouts are displayed on the map.
The "Color Coding" in the upper left corner of the screen allows you to display roundabout locations in different colors according to their location types or other factors.
Click on the location to display detailed information.
Index： The contents of the database are listed and can be searched for keywords by address, etc., or narrowed down by number of approach legs, etc.
The listed data can be exported as a csv file.
Dashboard： The number of roundabouts can be graphed by prefecture or by number of approach legs.
The graph can also be exported as a png file.
＜Data and explanation＞
Location Type： The location type of roundabouts was determined by cluster analysis based on digital national land information such as land use districts and public facilities.
For more details on the analysis, see the following paper;
"Progress of the roundabout implementation in Japan and the location characteristics analysis: Proceeding of Infrastructure Planning, Vol.66"
Rating： Good practices that may be helpful when planning roundabouts are rated with star marks (★: good, ★★: very good). Although each roundabout has a different introduction background and limitations, in order to ensure the objectivity, we have not considered these factors and have evaluated the actual roundabout mainly from a technical point of view.
inscribed diameter： Distance across the circle of roundabout?, including estimates based on measurements from aerial photographs.
The number of approach legs： The number of approach roads connecting to the roundabout
Date in service： The date when roundabout began operating as a roundabout