If you want information from the horse's mouth, go to www.bytrain.org This is the North Carolina Dept. of Tranportation's web site for rail matters. It appears to need updating, however, as in a lot of it the last update is a year or more ago.
I was under the impression that the third train was waiting on replacing some or all of the double track sections between Greensboro and Charlotte that had been removed in the 1960's. At that time the railroad was converted to alternating section of single track and double track, generally about 10 miles each. Between Greensboro and Charlotte there are four sections of single track, two north of Salisbury and two south of Salisbury. The web site shows the two north of Salisbury being restored at a cost of about $2 million per mile. This is supposed to have already happened, but so far as I know it has not as yet.
What has happened in the last five years is that the Raleigh to Greensboro section has been given signals, some long 45 mph sidings, and some other work to eliminate slow speed areas. The speed limit on this is now for the most part 79 mph instead of the former 59 mph. In addition, Selma to Raleigh has had its speed limit raised from 50 mph to 59 mph. At some point this section is also supposed to get signals, adn with them a hgiher speed limit.
I do not think there is any problem iwith NS on adding trains between Raleigh and Greensboro, only on the section between Greensboro and Charlotte.
The Charlotte to Greensboro to Raleigh, and on to Selma, Goldsboro, and Morehead City is owned by the state of North Carolian and is the North Carolina Railroad. In was leased by the Southern, or predecessor Richmond and Danville for 99 years in the 1890's or thereabouts. When that expired there was a good deal of negotiation between the state and NS, and that is putting it politely, after which there is now a new lease, so the railroad is operated by NS but owned by the state. This state ownership has a lot do do with North Carolina being able to do what they have in the way of funding and promoting passenger trains.
The amount quoted for Salisbury to Asheville sounds about right. This service is shown as simply being on hold on the NCDOT web site. NS is claiming congestion on the Salisbury to Asheville line and requesting a good deal of work on new and higher speed sidings. Some of the money is for increased superelevation on curves to improve the run time, which is not really an NS requirement, but needed to have a reasonable run time. Even with this, Salisbury to Asheville will still be fairly slow due to the mountainous terrain.
George