There are two codes "OSM_Roundabout" and "NDD_Roundabout"
OSM_Roundabout: A code that takes input ".osm" file for an area and extracts all the roundabouts in that area.".osm" file can be obtained from open street map website. As an example, code is implemented with 'test_file.osm'. The image file is in 'test_file.png'.
NDD_Roundabout: A function that takes input vehicle GPS coordinates and location of roundabouts (roundabout boundaries) and provides with interval when vehicle is within the roundabout boundaries. The roundabout boundaries denote a rectangular bounding box around a roundabout. Once the roundabout is obtained from OSM_Roundabout function, a bounding box can be created around it.