Two reasons were brought up.
1. Trump, Japan, and Taiwan cause "uncertainties" for China's shipping exports,
and
2. Shipping to Europe takes on the order of two months. A land route would cut that down.
There are already many ways to drive from China to Europe, and several rail routes. Google maps can show them.
What China’s One Road, One Belt is really about, is lining the pockets of Chinese communist politicians.
Just like corrupt politicians here (and everywhere) love big infrastructure projects, because of the kickbacks they can skim, and the favors they can dole out, so do the Princelings of the Communist Party of China.
They have an unlimited appetite for such boondoggles. Everybody and their cousin wants in on one. Its a get rich quick scheme for political insiders - which is how they mainly occupy themselves, when not oppressing the population or politicking within the Party.
I saw a similar show. I think it would be a good idea, but any investors would have to be nuts, given the politics and economies of pretty much every country it goes through until it hits Europe.
[Shipping to Europe takes on the order of two months. A land route would cut that down.]
#3 - Why were the Romans able to project their power over large distances? They had an advanced system of roads.