Project Controls at design stage, is it Essential to Project Success?

Project No: 1
A mega project, after many years of extensive unique design, tender return was 50% higher than the approved budget. Tried various value engineering exercise to reduce cost, several years passed project still not awarded.

Project No. 2
Another mega project, Project commenced, contract awarded without full design. Extensive changes during design development. Massive claim poured in from Contractors. Project stopped. Feasibility and rate of return in question. Not sure the outcome of the project.

Both project identity will be kept confidential.