The MDA (actually the MMDA) never has been "dropped" as a viable alternative, but the fact of the matter, at least as far as I can tell, is that it is a very hard sell. That became painfully clear when the community so quickly and vigorously embraced the idea of a tunnel after all of the efforts of groups like CPR1 to sell the public on the MMDA. I don't know of a single MMDA proponent who has come out and rejected the MMDA, although I know several who would be willing to "settle" for a tunnel.
From what I can tell, there were a few key reasons for the rapid acceptance of the tunnel.
First, the tunnel has no apparent environmental impact. In truth, there will be some, most likely on the approach from the north side where a bridge or a fill will need to be constructed. However, tunnels routinely get environmental approval with relatively simple environmental studies, especially compared to cuts, fills, or dumping a few million cubic yards of dirt and rock into the ocean.
Contrast the tunnel's easy environmental approval with the MMDA. The director of the marine sanctuary made it quite clear that there would be a big fight to prevent dumping of that much material (even the Sierra Club's estimate, not the outrageous Caltrans estimate).
Even the untrained lay person finds it easy to imagine that it might be bad dumping a bunch of stuff in the ocean. They may find it hard to imagine how road runoff from a freeway over the mountain might actually do more damage, but the lay person doesn't necessarily conjure up images of petroleum-based toxins in the runoff every time it rains and compare that to dirt and rock falling into the ocean once and for all.
Second, Caltrans did a very good job of scaring people about the size and nature of the MMDA repair.
Third, Caltrans did an excellent job of convincing people that such a repair could not be permanent. Caltrans is fixated (and a couple of their employees told me this directly) upon the "permanent" solution, and they couldn't say with 100% certainty that the MMDA would actually solve the problem, so it clearly wouldn't qualify as a "permanent solution". Besides, repairing a two-lane road rather than constructing a roadbed wide enough to hold six lanes of traffic doesn't suit their longer-term goal of providing a conduit for increased volumes of traffic.
Given that Caltrans had effectively nixed the MMDA in the public's mind, and given that a tunnel is clearly the lesser of the two evils when compared to the overland freeway, and given that Caltrans clearly wants to spend a lot of money on a major construction project, a tunnel seems like a clear winner. The groups promoting the MMDA were finding it to be a very tough sell, yet the tunnel is an easy sell. Go figure!
Indeed, given that 25% of the midcoast population has signed the petition requesting that a tunnel be given a fair evaluation, I'd have to say it's a runaway winner in the popular arena. Since Caltrans and our other governmental leaders don't seem interested in rational investigation of the alternatives, the court of public opinion (namely the polling place) might very well be the only means to a fair hearing on the alternatives, so a popular solution turns out to be quite important. In fact, if the MMDA is ever to have its day in court, pushing for the tunnel might very well be the thing that requires that Caltrans make a complete and impartial study of each of the alternatives.
Thanks much for writing in. I'll be interested to hear your reaction to this.
Editor, Montara Mountain Free Press