According to our rough estimate, based on 20 years of practice, earthwork can "lose" up to 50-60% of the budget. On reinforced concrete and finishing is exactly 30%. On the errors of re-registration in collisions, the cost of engineering increases by approximately 10%. It is for this simple reason, when the "evil customer" implements the BIM-model of the building, wild cries and groans begin on all sides.
BIM-control will now be on all state orders on a new standard, so the cries and groans will be especially epic.
Here I see the trace of all systems, I can get an accurate estimate for each node: and when I move or add an object I will receive updates in all project and working documents at once.
What is a BIM model? This is a three-dimensional model of a building where all systems are docked and tied together in one single plan. We put an outlet in the room - in the general estimate there was a new outlet and the corresponding cable meter. The error of this model is 2%. On paper, usually take a stock of 15%, and the surplus of this stock is desperately "lost."
Let's show you better examples than I will tell.