How data measuring is done on the Swiss small gauge tracks

Next to the regular Swiss railway network, there is a network of one meter gauge of around 1500 kilometres scattered across the country. Historically, not one of the 30 railway companies that operate on these tracks has a measuring train or car, so how can they make use of measuring data? Matthias Manhart, head of Rhomberg Sersa, explains their solution at the Intelligent Rail Summit 2021 in Bilbao.