> This implies that rail is running at capacity during the night, which I suspect isn’t true.

cry-laughs in German Oh hell yes we do run at nominal capacity, actually often enough above. The transit routes are fully booked all times of the year, the demand for freight transit is insane, and every bordering country is complaining that we can't get our shit together (to no one's surprise after 30 years of perpetual budget cuts).

The problem is: virtually all trans-European routes run through Germany. You can't avoid running through here.

That's like a lot of half knowledge someone would get by just listening to the media and anecdotal evidence. The net is not at capacity especially not at night. The freight trains that run at night have peak network capacity of only 30% even on high traffic routes like Hamburg - Berlin. There are close to no passenger cars running at night. At least inform yourself before writing a comment in the tonal voice you did.

Many German lines are running at 125% of capacity and above, including at night.

I do feel like rail in general isn't running anywhere near capacity. If it was optimized better with modern fluid signaling system, "packet based" routing of individual carriages, and way shorter headways, I think 10x the amount of cargo could be squeezed through.