From Sylvia Plummer, January 7, 2013
The One Tunnel option was brought up at the last Metro Technical Advisory Committee (TAC) meeting on 11/13/13. Metro has added a '1 tunnel' option, with and without trucks. Advertising it as 1/2 the cost and impact.
BUT Metro say's there will be a "second future tunnel" later.
So, there is really no change, except to drag out the construction phase.
Above is the url for the handout from the TAC Meeting, see pages 32 and 33 for information on the 'one tunnel' option.