“Expensive” is always a relative term. The Swiss have a good overground rail network and for example branch lines sometimes run combined cargo/passenger trains.

“Expensive” is always a relative term. The Swiss have a good overground rail network and for example branch lines sometimes run combined cargo/passenger trains. No need for dedicated tunnels here. Payoff in a city, especially with little existing rail infrastructure may look different. Hamburg for example tried to establish a 45cm diameter tube mail system in the 1960ies https://de.m.wikipedia.org/wiki/Rohrpost_in_Hamburg https://de.m.wikipedia.org/wiki/Rohrpost_in_Hamburg and that seems like a more viable concept for a city than a full fledged rail tunnel. The system ultimately failed for multiple reasons, but one was that the vibrations cause by cars and trucks damaged the tubes :(