IIRC, CTC was put in on the one track to facilitate operation of the Capitol Corrider train to/from Auburn, no doubt at state expense. Otherwise, passengers who boarded in Auburn in the morning would be returned to the opposite side of town in the evening as the two mains are quite a distance apart there. (Perhaps more CTC has since been installed that I'm unaware of.)
Also, new high/wide detectors have been installed to prevent surprises. It will be interesting to see if the increased traffic, stretches of single track, and weather combine to turn this into a fiasco. And there goes Amtrak 5 and 6's on-time performance . . .