Now, three years after the official dedication of the Central Artery/Third Harbor Tunnel, the state is reeling under a legacy of debt left by the massive project. In all, the project will cost an additional $7 billion in interest, bringing the total to a staggering $22 billion, according to a Globe review of hundreds of pages of state documents. It will not be paid off until 2038.
Contrary to the popular belief that this was a project heavily subsidized by the federal government, 73 percent of construction costs were paid by Massachusetts drivers and taxpayers. To meet that obligation, the state's annual payments will be nearly as much over the next several years, $600 million or more, as they were in the heaviest construction period.
Big Dig payments have already sucked maintenance and repair money away from deteriorating roads and bridges across the state, forcing the state to float more highway bonds and to go even deeper into the hole.