Civil infrastructure design software is the software in which engineers design roads, bridges, railways, metro lines and pipelines. These structures are called civil infrastructure. They differ from buildings in one big way: they follow the ground for many kilometres. After a structure is built, its model can be kept up to date with data from the real structure, as its digital twin.
Design starts with the ground. A survey team measures the land, often from the air, with drone surveying. The survey produces a terrain model, a 3D surface that gives the height of the ground at every point. Maps of land ownership, rivers, villages and existing roads come from a geographic information system (GIS).
Take, for example, a 28 km four-lane bypass being designed around a town in Rajasthan. The engineer draws the alignment, the line that the road will follow. The software works out the road's vertical profile: where it must climb, where it must fall, and how steep each slope may be under the highway design rules of the Indian Roads Congress. It then calculates the earthwork. Where the road runs below the ground, soil must be cut away. Where it runs above the ground, soil must be filled in. Say the first alignment needs 9 lakh cubic metres of cut and 14 lakh cubic metres of fill. The missing 5 lakh cubic metres would have to be dug elsewhere and brought in by truck. So the engineer shifts the line 200 metres and lowers it in two places. The new design balances cut and fill much more closely, so most of the soil dug out on one stretch is used on another. The software also helps design the two bridges, over a river and a railway line, and the drains under the road.
The model then passes to the owner and the contractor. A government owner tracks the bypass, with its budget and progress, in capital project management software.
After the road opens, the model has a second life. Sensors on each bridge measure strain and vibration, and inspection drones photograph cracks. These readings are added to the model, which becomes the bridge's digital twin. Engineers can then check how a heavy truck or a flood affects the bridge without going out to it, and plan repairs before a fault becomes dangerous.
How is it different from BIM software? BIM software models a building, room by room, on one plot of land. Civil design software models a long line across changing ground. Large industrial sites, such as refineries, use plant design software for their pipes and steel structures.