It does require really good maintenance-of-way work. Having all trains inspect the track is feasible. The latest round of Shinkansen trains does that. They're

It does require really good maintenance-of-way work. Having all trains inspect the track is feasible. The latest round of Shinkansen trains does that. They're moving away from running a Dr. Yellow track inspection train every 10 days.[1] [1] https://www.railway.supply/n700s-trains-to-be-equipped-with-infrastructure-diagnostics-equipment/ https://www.railway.supply/n700s-trains-to-be-equipped-with-...