The input data for calculation is survey data (either centerline only or centerline and edge lines) along existing roads. The program can import a number of file formats.
The accuracy of calculations is dependent on the distances between the measured points. The minimum required distance depends on the geometry of the road. Short curves and complicated alignment, with many consecutive curves, requires shorter distances between the measured points.
From experience, a minimum distance of 5.0m between measured points is likely to give a good result for most roads. If the geometry is less complicated, the distance can be up to 20.0m. Larger distances are not recommended.