The Big Dig was officially completed years ago, but one part of the gee-whiz engineering that made it so expensive is still causing problems and costing millions.
Among the early political decisions that helped make the Big Dig the most expensive public works projects in U.S. history was a pledge that construction would disrupt Boston's commerce as little as humanly possible. That meant tunneling under and around South Station without delaying, diverting or rattling the trains going in and out. To meet that challenge, Big Dig engineers came up with a fresh idea: Freeze the soil.
Cooling elements were buried in the soil under South Station and along Fort Point Channel, to protect another constituent, the U.S. Postal Service, from disruptions to its South Boston facility from work on the Mass. Pike extension. Other than the cost, the freeze the ground strategy seemed to work like a charm.
But here's a newsflash you don't expect to hear in mid-February: The ground is thawing, and that's a problem. More than two years after the job was officially concluded, the frozen soil under South Station is warming up and the railroad tracks are moving. State House News Service reports that MBTA officials have voted to extend a $346,045 consulting contract through 2011 to monitor the melting earth.
Already, railroad tracks have had to be realigned to accommodate the thawing, a process that is expected to continue through 2014. State officials say the consultant's contract will be paid out of a $350 million settlement paid by Big Dig contractors.
By the time the ground is fully thawed and the tracks realigned, we'll probably be dealing with the leaks that have already plagued the project, and more cracks and potholes will have appeared, confirming what has long been feared: The Big Dig, with its proven capacity to keep generating headaches, will never be really finished.
