The New Bedford -> Otis route allows traffic to bypass congestion on both Rt 3 and the canal access on either side. Feeder's from Otis -> Rt 6 in Sandwich and Rt 151 -> Rt 28 in Mashpee are also planned.
Plans started 4 years back; digging started in New Bedford last winter when the tunneling machinery that made the Deer Island outflow tunnel in Boston harbor was barged south. I'm not sure if a second piece of machinery has started at Otis yet.
The Falmouth -> V.H. tunnel is planned to go underground where Rt 28 in Falmouth goes from 2 lanes -> 1 lane; I'm not familiar w/ exactly where in Vineyard Haven it is supposed to come up.