As you aware scanning is a process to identify an object without touching it...! In the construction where the object that we can't touch? Yes.... there is.... Can you touch at the center of a heavy traffic road? Can you touch a mountain top where you can't climb? Can you touch a tree top where you can't reach? Here is the solution.. SCANNING. We can obtain the coordinate and elevation of such matters without accessing it. The data can be get as 2D drawing and can be as 3D photograph. Usually scanning provide 1cm accuracy depends up on the distance and height. Scanning have its own limitations even though while consider the practical difficulties and safety hazards of some situations, it is better and adoptable. Scanning of road is common for Non Disturbed Road Crossing (NDRC/NDM) to get the elevation of road in pre drive and post drive stages.