I was never convinced that the city needed anything more than a surface street. It's a little dicey putting any tunnel there against the waterfront in landfill in an earthquake-prone area. Moreover, it was never clear that the traffic patterns would have been improved by any sort of tunnel option. The whole thing always had the feel of a land grab for real estate developers, too. On top of that, a tunnel was really the worst for Seattle since it wouldn't help anyone get into or out of downtown, just through downtown.