[mkl]

Japan, Germany, France, China, and the UK check their tracks at high speed. I don't know if Spain does, but there are news articles about them ordering such an inspection train in 2019: https://www.railjournal.com/infrastructure/adif-orders-high-...

https://de.wikipedia.org/wiki/RAILab

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

https://en.wikipedia.org/wiki/SNCF_TGV_Iris_320

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

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