On my way across Russia by train I spent hours staring out the window at the passing scenery, and in that time I found plenty of railway staff looking just as intently at the tracks.
Inspection crews walk the tracks, using specialised equipment to check the rails for flaws.
The snow doesn’t keep them from their work.
But passing trains do – thankfully the equipment is easy to move off the tracks.
To make their job easier on long stretches of track, self powered track inspection vehicles are used.
Russian Wikipedia has more on the «Автомотриса дефектоскопная» АДЗ-1 pictured above:
АДЭ-1 is an inspection railcar that uses ultrasound and magnetic flaw detection of rail flaws built by OAO “Kaluga Track Machine and hydraulic drives» (JSC «Kalugaputmash”).
The railcar is self-propelled and has a four person crew. It is maintained in all weather conditions and at any time of the day at an ambient temperature of -40 to + 40°C, with ultrasonic testing being possible at temperatures from -30 to + 40°C.
14.48 metres long and weighting 45 tons, the railcar has a 200 kW engine and 20 – 20 bogies, allowing a maximum speed of 80 km/h.
Wikipedia has more about the detection of rail flaws.