“The AC is one of the constant problems with cars along with the door mechanism.”
It’s the vibration. Knocks things loose.
I wonder if they have the same issues over seas. Continuous welded rail isn’t new technology. If they do it in rural WV for short lines for coal, it should be in use for subways.
I’m not convinced vibration is the issue. Car parts and assemblies are sourced internationally. Before Bombardier bought Adtranz their stock was in the mid $30s. They’ve never broken $5 since if IIRC.
Low buck equals cost cutting somewhere.