That's another part of the infrastructure, though: We just don't have enough rail as well as backup rolling stock.

And as the federation finally decided to spend some money it's going to get worse in the next decade or so due to outages due to new constructions being linked up to the old stuff.

As to the age of the infrastructure -- I mean it's the railway. If a rarely-used branch line still uses mechanical interlocks and there's no need to upgrade the capacity then the line is going to continue using infrastructure build in the times of the Kaiser. It's not like those systems are unsafe, it just might be the case that unlike in the days of ole those posts with a gazillion levers aren't manned all the time so you'll see an operator drive to it with a car while the train is on its way. Which really isn't that much of a deal when the branch line goes to a, what, quarry maybe sending out a train every two months or so. Certainly better than to demolish the line and use trucks instead.