The correct answer to this open question is the following.
Although there are no options attached, we can say the following.
This new tunnel revolutionized transportation in Europe and overcome this physical barrier because the Swiss engineers built the world's deepest and longest tunnel in the world, increasing the effectivity of train freight transportation across Europe.
We are talking about the Gotthard base tunnel, in Switzerland. According to the article "Swiss create the world's longest tunnel," was so complex to build that engineers and workers lasted 20 years to complete. It is a tunnel for trains. It has 35 miles of longitude and crosses the Alpes mountains.