A Flyover or an overpass is a bridge, road, railway or similar structure that crosses over another road or railway. The first flyover in India was opened on 14 April 1965 at Kemps Corner in Mumbai. Railway overpasses are used to replace level crossings (at-grade crossings) as a safer alternative.

Using overpasses allows for unobstructed rail traffic to flow without conflicting with vehicular and pedestrian traffic. Rapid transit systems use complete grade separation of their rights of way to avoid traffic interference with frequent and reliable service. Railroads also use balloon loops and flying junctions instead of flat junctions, as a way to reverse direction and to avoid trains conflicting with those on other tracks.

With the increase in the traffic and the requirements of additional lanes of rails & roads there has been an tremendous increase in the requirements for the flyovers in past few years. The surveys for these usually require precise detailing since most of them are with complex shapes and geometry.

At "Prashant Surveys" we use the state of the art 3D Mobile LiDAR Technology using "Leica Pegasus One" and "Leica Pegasus Two" mobile mapping system. Most of these flyover surveys can be conducted within a day which includes dense 3d point cloud data collection along with photographs.

The Topographic Survey drawing or the as-built drawing of the proposed or existing site can be prepared up to the accuracy of +/-2 cm which is sufficient to prepare a detailed drawings to the scale of 1:500 or 1:1,000.