The new rail route, which will traverse Kazakhstan, a part of Russia, Belarus, and the EU before entering the UK via the Channel Tunnel, is part of a rapidly growing network that now consists of 39 rail lines, now linking 15 cities in Europe with 15 in China. London became the 15th European city in the ever growing Eurasian rail network.
The economic advantage of these trains justifies the massive investments required to fund the construction. These trains and routes will cut the travel time of products between Europe and China in half when compared to shipping by sea. Also, compared to shipping by air it will be drastically cheaper. Currently the rail and trains are to be used for high-value products that need to be transported as quickly as possible such as premium agricultural goods, fresh meat, electronics and others.
While these direct trans-Eurasian block trains were initially developed by commercial entities purely for economic reasons, they soon took on a geopolitical dimension of their own. In 2013, China announced its Belt and Road initiative (BRI), which pledged over a trillion dollars to bolster the development of transportation, energy, and trade infrastructure from the west of China to the east of Europe, and the establishment of these rail lines soon became its vanguard -- which is attested to by the fact that the entire network is subsidized by the Chinese government.