Wow, that's a really big gap. No wonder it derailed

What are the some of the ways that tracks are monitored for fractures like this? It must have been pretty substantial in order to be described as "complete lack of continuity". Makes me think of literally electronic continuity tests -- are those ever used in this context? Or how about cameras mounted on trains using image processing? Or drones?

It seems a shame that a few other trains passed beforehand with this anomaly in place and yet it went undetected.

My gut feeling says a lot of fatalities could have been prevented with a physical barrier between both tracks. Shouldn't this be mandatory with high speed trains?

While these events are statistically very rare, it is worth remembering that there have been two separate events in the past twenty years in Spain where high-speed trains have derailed leading to multiple fatalities [1][2]. In contrast, the Japanese Shinkansen has a spotless record since its introduction in the 1960s [3]. Not a single fatality due to a crash or derailment. And that's in a country with a much larger population and much higher passenger count per year.

What do they do differently?

[1] https://en.wikipedia.org/wiki/Santiago_de_Compostela_derailm...

[2] https://en.wikipedia.org/wiki/2026_Adamuz_train_derailments

[3] https://en.wikipedia.org/wiki/Shinkansen#Safety_record