So yes, this seems to be a real problem, as it is possible to arrange a train with with 256 axles with this type of car that does not violate the maximum length restriction.
> I was wondering if this could be an actual problem.
In Switzerland? Probably not. In other places definitely, large-countries (USA, Canada, Australia) freight and coal/ore trains are hundreds of cars long (and each car has at least 2 bogies of 2 axles), the record is 682 cars and 8 locomotives.
Although not all rail systems in all countries use axle counters for presence detection. In the US freight industry we use track circuits - https://en.wikipedia.org/wiki/Track_circuit
That's not a replacement, that's the older technology.
Axle counting guarantees that there isn't a detached, derailed wagon fouling the line, or a wagon with dirty wheels which aren't completing the track circuit.
Those 8 locomotives can be controlled by a single team of people. Additionally it allows greater freight throughput because you need to maintain minimum distances between trains. It's actually extremely uncommon where I live to see a train with a single locomotive.
Well technically that specific train was a stunt (at the time BHP Billiton's regular run used 336 cars and 6~8 locomotives, now 264 cars and 4 locomotives), other commenters have answered as to why you'd want to run longer trains (and AFAIK modern trains rarely run a single locomotive these days, a pair is just more efficient and convenient even on passenger trains)
- 2 axle cars must be longer than 5.76m
- 4 axle cars must be longer than 10.92m
- 6 axle cars must be longer than 16.38m
Found this 6 axle car with a length of 15.0m: https://de.wikipedia.org/wiki/Flachwagen#S-Wagen_f.C3.BCr_sc...
So yes, this seems to be a real problem, as it is possible to arrange a train with with 256 axles with this type of car that does not violate the maximum length restriction.