Actually, that's not the route you want to take; the traffic lights near Alewife at the 16/2 junction are a nightmare in the morning.

Follow Mass Ave up to Route 60, and get onto 2 from 60. You'll deal with Route 60 traffic, but it's not the parking lot that Route 16 is between Mass Ave and 2 in the mornings.

I used to take the 79 to work, and it would take as long to get to Alewife as taking the 77 to Porter. (I live just over the border in Arlington.)