Well, half of it anyway... After almost 20 years of construction, the underground northbound lanes of the I-93 Central Artery (which runs right through downtown Boston) are open to the public. Officially called the "Liberty Tunnel," the total distance of the tunnel is a little over 2 miles in length. My wife and I decided we needed to go to Costco yesterday, mainly just so that we would have an excuse to take the new tunnel. Traffic, even though it was a traditionally dead Sunday, was very heavy. The tunnel entrance starts right before South Station and emerges near the Fleet Center, onto the brand new Leonard P. Zakin Bunker Hill Bridge. Only time will tell if this $15 billion project pays off. Has anyone else driven through yet?