A jackknifed tractor-trailer has completely shut down I-93 southbound in the O’Neill Tunnel, turning Friday morning into a nightmare for Boston commuters. With all lanes closed near Exit 16, traffic is being rerouted and the Zakim Bridge is gridlocked. If you’re heading into the city, you’ll want to rethink your route—delays are massive and there’s no word yet on when things will clear up. Anyone else stuck in this mess or have a secret detour to share? Let’s help each other out and keep the updates coming! #Transportation #BostonTraffic #O’NeillTunnel