When the thing you want to fund is infrastructure, a huge portion of the cost is the real estate, which has to be reimbursed at market rates, so the projects be

When the thing you want to fund is infrastructure, a huge portion of the cost is the real estate, which has to be reimbursed at market rates, so the projects become more expensive as well, even if at a slightly slower rate. However, big projects have to be justified in multiple ways: environmental impact statements and cost/ benefit analysis are two that are almost universally required throughout the US. Especially in expensive NIMBY cities, a sudden spike in costs (or any other significant change) can be a political tool for opponents to claim those justifications are no longer valid, as a way to halt or delay. And this being government, there's a good chance that the multi-year planning, approval, and funding process assumed a lower rate of inflation, and now some projects may simply not have enough money and have to start the process over.