In case you are reading this in 2020, just take the hyperloop :)
One of the companies vying to make Elon Musk's transportation dream a reality has signed a deal with the government of Slovakia to explore building a three-country Hyperloop. Crowdsourced engineering project Hyperloop Transportation Technologies (HTT) will look into a route that links three European capitals. From Vienna, Austria to Bratislava, Slovakia, and from Bratislava to Budapest, Hungary.
While the idea of a three-country Hyperloop might seem extreme, the distances between the three cities is actually fairly trivial. Vienna to Bratislava is a 35-mile straight line, or 50 miles by current transport routes. Bratislava to Budapest is a 100-mile straight line, or 125 miles by transport. Both are well within the realm of possibility.