Can you say, "Big Dig"? The way we'll know is when the cost overruns begin -- or when the toll increases start...
Toll roads in Texas have tended to be just the opposite. They get built faster and significantly under budget compared to public sector projects. The Hardy toll road in Houston is a good example of that. It was finished a year ahead of schedule and $50 million under budget. I've never seen state owned highways that got built as fast.
The "Big Dig" is a financed by the federal fuel taxes paid by drivers all over the US. At least with toll roads, the money doesn't get allocated according to which senator has seniority or which one is the party leader. I wonder how many people have died in other states due to the diversion of highway funds away from them postponement or cancellation of highway improvements.