It seems that despite best efforts, big projects always seem to go over budget. And the bigger the project, the more they go over. Actually, these projects don’t suffer from being over budget as much as being underestimated.
The bigger the project the more stakeholders’ want it approved, and to get it approved they want, demand, a lowest number. Vendors want the project at any cost. They will chase each other to the sub-level basements to get the work. Additionally, sub-contractors and support vendors are negotiated with separately, leaving little room for collaboration among the most important players. There is a “get the work at any cost” mentality. Everyone is independently driving toward an impossible best-case scenario. Nobody left anything for wiggle-room.
Applying realistic estimates to a project requires confidence and the courage to occasionally walk away. One thing worse than not getting a project, is getting a project at a loss–that could sink you.