It's a combination of ageing cars that need service or are retired, combined with several hundred that were modified for and being used only for the medium/tall roof Transits. On top of it, there's a nationwide shortage of locomotives as well, which is why down south along the border, a few of the railroads are using power leased from Mexican railroads (NAFTA at its finest). Railroads are having to prioritize even more now, especially with the boom of oil trains coming out of the plains states and central Canada. It's a perfect storm, and it's actually hurting the growth of the economy as a whole.