A “TIN surface” refers to a digital representation of a terrain or landscape in three dimensions using a Triangulated Irregular Network (TIN).
A TIN is a data structure used in cartography and geographic information systems to represent the topography of a given area. It consists of a series of triangles connected by a network of control points or vertices. Each vertex has associated x, y, and z coordinates (latitude, longitude and height).
For this case we will make a TIN surface but instead of being topography data it will be the project data to build a linear work with a return roundabout.
In the video below you will find a clear procedure, we recommend that you take a few minutes to learn the whole process in a simple way.