Think about it from the other side of the fence. My experience was with weapon systems but to a certain extent it does apply to roads.
Because of THE RULES only fixed priced bids are acceptable.
As a contractor you are being asked to quote on the complete price for a new product build, even though you haven't designed, tested or built anything like it before. The price you quote needs to include the cost of upgrading a bunch of existing equipment to support your new product. You have no idea what the current state of the existing equipment is.
You have three choices:
- Quote a huge price that fairly covers every possible risk, and get told it's too expensive.
- Quote a small price and caveat the hell out of everything and get blamed when the initial conditions or complexity turns out to have been misunderstood or misrepresented.
- Go bankrupt.
You actually even see the same decision being made by normal employees at work. "Sure boss, I can do it in three weeks, as long as Dell delivers on time" would be an example of option (2) in action.