The cost overruns for the Big Dig look outrageous to us now ... but many big projects of the past have cost much more than the original estimates, ... (But) cities really don't have much choice. Americans have chosen to live in cities; we have no choice but to keep them livable. And despite the enormous headaches that Bostonians are experiencing now ... in 20 years they're going to be proud as hell, because they'll have the most beautiful and livable downtown in the country. James Tobin