What does super expensive mean? Expensive is a relative term. When weighed against the costs of other options, tunneling consistently comes out ahead on a cost basis. This is proven by the fact that tunneling projects are undertaken regularly across the world.
If that "proves" anything, it's only that public entities spend money according to priorities other than thrift.
But really, your response to a plea for a single example of an economically-defensible tunnel project was "tunneling consistently comes out ahead on a cost basis"? You never took rhetoric, did you? It's not as though I asked a question that someone "in the industry" wouldn't have the background to answer.
Public entities do not spend money according to priorities other than thrift, in general. Rather, they assign dollar values to everything (sometimes irrationally) and then compare based on a dollar valuation. Some entities pretend to not do this by obscuring things with a neat naming convention like a "contractor score" or "ranked qualifications" but, in the end, it's all about money because the public has people, such as yourself, who are ready to hang them in a second if they think their money is being mismanaged.
The reason I don't give a single example of a tunnel project is because they are, quite literally, all over. Your local water/sewer district has probably put in tens in the past year. If you live in the Bay area, Caldecott's fourth bore has just been completed successfully (on time, under budget) and this installation was obviously much less costly than blowing up the mountain. If you live out East, Liberty University just completed a jacked box tunnel install that was less costly than the alternative of rerouting train traffic or continuing to use a less safe at-grade crossing.
Are there examples of tunnels that have gone awry? Certainly, and I'm sure you're more than willing to rattle off a few results that you found on Google. The fact is, good and cheap (relative to the other options) tunneling jobs happen all the time, around the world.
Your use of scare quotes does not diminish the fact that you are completely ignorant of the pros and cons of tunneling and that you are arguing from that position of ignorance.
Around here, we dig a trench when we want to set a pipe or a box culvert. Sometimes it's a deep trench, but it's never a tunnel. (I was on a road job where a culvert trench wasn't a trench but rather a valley.) The tunneling I see is that of the "gas line under the highway" variety, which if that's what we're talking about, makes sense -- it takes two guys a few hours. It's not multiple lanes of traffic through a mountain.
But thanks for answering the (ignorant, obviously...) question!
