The new Metro extension out of DC to Dulles airport is literally crumbling... concrete is failing, the maintenance yard is sinking into the ground, plus it's over-budget and over-time. For the concrete, the apparent answer is "we'll inspect it more" instead of holding the contractor accountable and making them replace it. Because reasons.
Boston recently spent $21B on the Big Dig project. It was shittily built. It leaks, and the tunnel ceiling collapsed.