When Boston's central artery opened in 1959, it recklessly careened through the density of downtown, awkwardly tearing urban tissue (but offering the driver with a perhaps exhilarating ride grazing past buildings). The elevated highway, designed to carry 75 000 vehicles per day, today channels 190 000. The antiquated six-lane highway will be replaced with an eight-to-ten-lane underground expressway directly underneath the old road. After the tunnel is complete, the elevated highway will be demolished. Traffic capacity and access to/from the city is to be maintained throughout the entire project. The underground tunnel will carry 245 000 vehicles per day by 2010.

The old road has 27 on- and off-ramps; the new tunnel will have 14. Through excavation, 2.9 million cubic yards of clay will be made available to cities to cap their landfills that have reached capacity. The entire project will create 150 acres of new parks and open space in Boston, allowing for the 2400 trees to be planted downtown. For a glorification of American technology and goodness, see the official big dig website.