While cycling in western Czechia recently, I noticed this road marking on many of the rural roads I used, usually at intervals of 500 m to 1 km. What does it mean?

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    IDK about Czech but in UK there are markings which are recognised by surveying vehicles, like this. Aug 14, 2022 at 16:28

1 Answer 1


Those are "Ground Control Points" for surveying vehicles.

These markers popped up on various roads all across Czechia in the last few months, leading to a lot of confused people. As a result, they were quite extensively covered by various Czech media outlets. The most comprehensive article I have found is here, but it is in Czech, so you likely have to resort to Google Translate (I couldn't find anything in English).

In short, these markers are used to collect data for the Digital technical map of the Czech Republic (in Czech again), which is a map of all kinds of public infrastructure (roads, railways, water/power/gas lines, bridges, buildings, utility poles, etc.). The markers are used by surveying cars to match up and align captured images, stitch them together and place them on a map.

(Apparently, there's a whole conspiracy theory going on around these markers. Some think those are "guidance QR codes" for Russian nuclear ballistic missiles, so people have set out to paint over the markers to thwart any potential nuclear bombing.)

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