Actually, from what I can see in the Portland assessor's database, both the PTC and the Greyhound station are listed as taxable. Portions of the PTC area are owned by NNEPRA and are exempt, but the PTC and its parking areas themselves are not. The areas indicated in the article as potential sites for NNEPRA to move to are, AFAIK, already exempt as either railroad (in the case of the west-of-the-bridge site) or city property (the International Marine Terminal and the Fish Pier parking lot), so that's a wash.
I've heard three main arguments for moving the station: that the current location becomes untenably awkward once Portland stops being the terminal stop for the Downeaster, due to the backup-and-reverse that will be needed to continue to Brunswick; that NNEPRA would like to be able to offer more than one track for boarding which they currently have no room for; and that the current station does a poor job of serving inbound trips to downtown Portland due to its location (i.e., you can't get off the train and easily walk anywhere interesting).
The Downeaster article said that NNEPRA is planning on making a presentation to the city council's Transportation Committee at Tuesday's meeting. That committee's web page is here
; the meeting agenda has been posted and there are two rail-related items: NNEPRA's presentation (for which no materials have been posted) and discussion of a staff memo regarding a potential City Rail Policy. The staff memo (which the web page makes available) is a brusque series of bullet points that includes, among other things, mentions of stations for both intercity and commuter rail.
To touch on the "Concord passenger makeup" question, I'll refer to the things that made them successful in the first place after they first came to Portland (at which time Greyhound was the only game in town and provided a lot more than 3 trips/day). First, they provide direct service to Logan, which is immensely popular judging by the lines that form when those buses are announced. Second, both their routes (to Logan and to South Station) are non-stop; Greyhound stops in Portsmouth, and for a while in the 80's they also stopped in Newburyport on all runs (GL used to offer a Route 1 local as well, but I think that's long gone). Third, as gokeefe alluded to, they are perceived as a higher-quality operation, with cleaner buses and stations than GL and the enroute movie and wifi provided (it's worthwhile to remember that at the time then-Concord Trailways first came to Portland, GL was still running to their old Arlington St. station in Boston, which was a horror show). I'll also mention that when I went to the Portland station last year to pick up my tickets for the Lake Shore, the Amtrak ticket agent advised me that the best way to connect to it was just to take Concord, rather than connecting via the Downeaster (I had inquired about their flexpass tickets that were good on both the DE and CCL, and she said they'd rather not sell them as too many customers didn't realize that bus tickets weren't reserved seats).
"...And then I thought, every time some company creates a more powerful locomotive does Superman become more powerful as well or is he stuck at 1938 locomotive power levels?" - A friend of mine elsewhere
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