Here in Munich, Germany, public transport in the city center is based on a very small number of tunnels for underground trains. There is one main tunnel for cit

Here in Munich, Germany, public transport in the city center is based on a very small number of tunnels for underground trains. There is one main tunnel for city traversal, and about 5 or so underground tunnels. Together they bear a large part of the commuters traffic. Currently, the construction for another large train tunnel is about to begin. From that perspective, one wouldn't need an extremely large number of tunnels to vastly enhance traffic across a dense populated area. So when Musk is building tunnels, they aren't direct replacements for highways. They are either train tunnels, or hyperloop tunnels, or if they are car tunnels, they are for autonomous electric cars, which are driving literally bumper to bumper across the tunnels. So they would carry much more traffic in a more organized way than the normal highway. So it all comes down to whether he manages to improve the boring process to a point where people would want to digg more tunnels as with current methods.