You've been seeing billboards, ads, and news reports about it. The Sumner Tunnel that brings traffic from East Boston into downtown Boston is closing for almost two months straight. But why now? And what do crews have to do that will take two whole months, sparking some serious traffic troubles? MassDOT Highway Administrator Jonathan Gulliver gives us a behind-the-scenes rundown of what's getting done in the tunnel, and details alternative travel methods for commuters.

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