The measurement trains drive slowly in the night.

mkl · 2026-01-26T06:42:10 1769409730

They can go at high speed:

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

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

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

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

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

N19PEDL2 · 2026-01-27T13:15:58 1769519758

Italy: https://decode39.com/3045/diamond-fs-diagnostics-train-luigi...

mitthrowaway2 · 2026-01-26T08:06:35 1769414795

Indeed!

> Line inspection is carried out at full speed, up to 270 km/h or 168 mph on the Tōkaidō Shinkansen and 285 km/h or 177 mph on the Sanyō Shinkansen

Azrael3000 · 2026-01-25T23:03:50 1769382230

Not necessarily, the measurement train my company develops can go up to 100 km/h and measure certain rail features every 5mm at that speed.

lefra · 2026-01-26T06:00:20 1769407220

100 km/h is slow compared to passenger train (even non-high-speed ones). Depending on how packed the schedule is, it might not be possible to analyse track during the day without causing backups.