https://www.cnn.com/travel/article/great-tunnels-2016/index.html

Multiple tunnels in the world are masterpieces of engineering such as the longest tunnel in the world, the Gotthard Tunnel. The Gotthard Tunnel is underneath the Alps in Switzerland. It cost a massive $7 billion dollars to construct and was a result of the heavy traffic in Switzerland. Because Switzerland is located in the center of Europe it is one of the biggest traffic intersections of the world. Thus, in 1998, Swiss voters decided to construct two tunnels both larger than every other tunnel before. The result was two masterpieces.

This relates to engineering because the engineers had to brainstorm and use the engineering process to solve possible problems that popped up. These possible problems include cave-ins, fires, and explosions. Luckily, the engineers in charge of this project were smart and good at decision making and therefore the tunnel was completed with a relatively small amount of accidents.

https://www.youtube.com/watch?v=QaTN_R1b00I