Data don't lie: At its current 3mm passenger-miles/month rate (and assuming that about 50% of those PMs are generated with Maine passengers and 50% of passengers travel as couples), the Downeaster has reduced traffic on the Maine Turnpike by about one percent. Not exactly a congestion reducer (oh, by the way... at that passenger count, the train averages less than 60 passenger-miles per gallon of fuel - buses get 150-250 PMG. In other words, when comparing the Downeaster fuel performance to bus service, think Hummer vs Prius! Sad but I digress...
As a wise man once said: The data doesn't lie, it exaggerates. That 150-250 PMG figure for buses seems like it could be a product of most buses going express (or close to it) from beginning to end point-- most if not all Concord Trailways buses, for instance, doesn't stop between Portland and Boston. That's a sure way to boost your PMG.
Back to the "congestion" issue. Even if the train was able to double it's impact in reducing car trips POR-ROCKLAND, it ain't gonna make a dent in any of coastal Route 1's perceived congestion issues. PS - Average daily car count through Thomaston on Rt 1: 9,300. Spreading that daily rate over just a 12 hr period per day would yield an average a car every 9 seconds or so in each direction. Not exactly gridlock. MDOT categorizes seasonal traffic volume fluctuations on RT 1 in Thomaston, Rockland, etc. as moderate.
To me it's both a land use and a congestion issue. Cars promote sprawl, and greater Portland has some of the worst sprawl in the nation. One solution (and by no means the only one, and admittedly probably not even the most efficient one) is to get them onto trains and by extension, start planning development around rail or other forms of public transportation.
Again, I can't emphasize enough the disastrous turn Maine has taken in terms of inefficient land use. The environmental degradation is already staggering, not to mention the changes in quality of life. Maine is much more like the rest of the country than it has ever been before, and it's unchecked suburbanization has a lot to do with that. Curbing automobile use is one way to fight that. Certainly there's a worthy debate to be had about the different ways we want to fight sprawl and how much we want to spend doing it. To me the environmental (not economic) efficiencies of steel wheels on steel rails make a lot of sense.
On congestion: As a baseline concept, just so I'm clear about where I'm coming from conceptually, I think that good regional planning should anticipate growth and all the problems that it brings, not respond to it (OK, it should do both, but what I'm saying is that building new rail lines, roads, etc as a sort band-aid response to congestion that's already there is a sure way to chaos)...
Cowford, much like the PMG figure, I think that 1% reduction of congestion on the Turnpike figure is a canard. First, we shouldn't expect a train to reduce highway use, at least in the short term, because highway use virtually never diminishes. To use an imprecise economics metaphor, its demand is inelastic (and yes, for all you nitpicking economists out there, I know that it's price that's supposed to be inelastic, not demand...it's a metaphor
). We can, however, expect a train to slow the rate of traffic growth. Indeed, this is exactly what's happened, albeit modestly, on the Maine turnpike. I'm not an economist or a planner, so I can't say that the correlation equals causation, but it is suggestive.
And that statistical uncertainty is the real difficulty in the cars vs. buses vs. trains argument. Mass transit's success is measured not by reductions in traffic that already exists, but by reductions in traffic that doesn't exist yet. I don't know of any easy ways to measure that.