Mr. Paul Sheridan:

That was the original intention of the public works contract - a lump sum, fixed price to deliver certainty - but to get certainty you have to have fixed information. Unfortunately, in complex construction, you cannot fix the information. Every form of contract in the world has a mechanism to deal with change. It is part of the industry. These projects go on for ten years from inception right to delivery. You need that flexibility. You want to make sure you eliminate dispute and increase collaboration when dealing with those issues. To mitigate them happening, you get the design right.