A Curved Regular Grid (CRG) road is comprised of node data on a centerline/curved reference line (u-axis) along with node data along lines orthogonal to the centerline (v-axis).  The u-axis has nodes ‘ubeg’ and ‘uend’ denoting the beginning and ending nodes of the centerline.  The orthogonal lines to the centerline/reference line have values ranging from ‘vmin’ to ‘vmax’. (x,y) coordinates are obtained by querying the (u,v) coordinates.  (z) coordinate is obtained by querying the (x,y) coordinates from the previous step.

A Regular Grid Road has data points that are equally spaced in the x- and y- directions.  The grid data are defined by:

Regular grid data files can be combined with curvilinear road centerlines to form TeimOrbit data files of type ‘3D Spline’.  The road centerline, as defined in the RDF-file, is used as curvilinear x-axis of the grid.  X data points are equidistant along the centerline with a spacing of ∆x.  The x-coordinate starts with value 0 at the beginning of the road, which is defined by the first data point in the RDF-file.  The grid’s y-coordinate is chosen perpendicular to the centerline, in other words it coordinates with the centerline’s normal in the road surface.  Positive y- values define grid points that are located on the left of the centerline, if viewed along the direction of increasing x-values.