In Europe, . The railways connect London in the UK with Amsterdam in The Netherlands, and you can travel from Zurich in Switzerland all the way to Budapest in Hungary. But, one area that has always proven a sticking point is when travelers want to get from Austria over the alps and into Italy. Now, .

It’s called the Brenner Base Tunnel and, when it opens, it’ll become the longest underground rail connection in the world. Impressive stuff.

The will take travelers from Innsbruck in Austria across the alps and into Fortezza in Italy. When connected to the underground rail systems in Innsbruck, the total length of this underground railway will be 64km (40 miles).

To build this monster rail link, engineers began excavating beneath the mountains of Austria in 2015. They are working to construct three tunnels as part of the system, the first is a service tunnel that will also be used to assess the ground conditions.

Construction workers will also drill two rail , so that trains can run into and out of Italy. According to YouTube channel The B1M, the cost of all this drilling is set to reach a cool $11 billion.

There are few who would doubt that this is an impressive undertaking, and one that is sure to delight rail passengers traversing . But, why is the new multi-billion-dollar project even needed when there are already enough train lines to go around?

Well, according to The B1M, the Brenner Pass that links Austria and Italy is one of the most heavily congested routes in the alps. It is one of the few roadways that can be traversed year-round, so is very popular with freight crossing the mountain range.

What’s more, the Brenner Railway line that covers the route is only currently capable of carrying a third of the freight that travels this route. That’s thanks to the altitude it rides at and the reduction in train speed that this entails.

With its two underground , it’s hoped that the Brenner Base Tunnel will be able to ease the load on roads and highways once it opens.

But when will the audacious ordeal be completed? Well, construction on the tunnels began in seven years ago now, and workers have three main routes to excavate, as well as escape chutes. They will also construct emergency stations within the tunnels. So it isn’t going to be a quick job.

In fact, says that the tunnel won’t open to trains until 2028, when the European Union hopes it will help preserve “the future of the environmentally vulnerable alpine region.”