Something like this only costs $15m because the incentives are crap. You know it if you've driven past any road construction project. 90% of the people at any given time are standing around. You have to pay just as much for a person to stand around as you do for them to be doing useful work.

Fixing the incentives is not easy at all. There are a lot of "good reasons" why this happens. Many of them are failures down the line, but no one at the contractor level pays the price for not mitigating them, so they don't. If a truck doesn't arrive on time, you could find something else useful to do, or you could just stand around waiting. If you/your company is paid by the hour, it's more profitable to stand there.

Your company could also charge the trucking company for arriving late, or the concrete plant for making them wait. This is not customary in the industry though.

Suppose you fixed all of this though. For a given number of construction projects, you'd need way less labor. If profits are a percentage of costs, less labor means less profit. Making things more efficient means the construction company has to lay a bunch of people off and make less profit, so their incentive is to convince the government that inflated costs are reasonable.

I'm not sure what the solution is. Laying people off is painful. However, one thing you might do would be to do more work for the same money, or higher quality work for the same money.