> how do you mess up a straight line?

One thing I learned working on a system that did train positioning for the 7 Line subway in NYC is that train systems are a lot more complicated than just straight lines. They are complicated networks with custom signaling and the trains don't necessarily travel on the usual side in the usual direction at all times.

That said, in this particular case it basically was just two straight lines side by side and one of the trains derailed and travelled into the path of the other track.

Trains don't often derail on straight sections, likely either someone fucked up really bad on rail maintenance or someone sabotaged the rail.

> For the last decade, an average of 1,300 trains derailed each year (in the US), accounting for 61% of all train accidents.

https://usafacts.org/articles/are-train-derailments-becoming...

> In 2024, there were 1,507 significant railway accidents in the EU, with a total of 750 people killed and 548 seriously injured.

https://ec.europa.eu/eurostat/statistics-explained/index.php...

https://en.wikipedia.org/wiki/Derailment

...when they come off the tracks.

a high-speed train travelling from Malaga to Madrid derailed and crossed over onto another track