The concepts are now posted on the project web site, and can be grouped as seven "rebuild" options along with four other "reroute" options that would bring about the abandonment of the tunnel altogether (and, it must be said, are probably a just smidge less likely to be one of the alternatives chosen).

Three of the rebuild options are along the lines of what's been discussed for more than two years now, which would be the running of a temporary track in an open trench while the expansion work is done on the existing tunnel. While having the trench on the south side of the tracks (Concept 2) has been the "default" discussion and has to be assumed to be CSX's preferred choice, Concept 3 shows the possibility of running the trench on the north side of the tunnel, which would be right next to the Southeast Freeway (and which I'm imagining would run into some issues with having to make sure all freeway supports are adequately protected). Concept 4 runs a "serpentine" trench both north and south of the existing tracks.

Concept 5 is an intriguing new notion, where a second permanent tunnel would be built parallel and south of the existing one. There's also the idea of just widening the current tunnel either while trains continue to use the tunnel (Concept 6) or with freight traffic temporarily rerouted either to Union Station (Concept 7A) or outside the District entirely (with a route shown that would take trains from Richmond through Ohio and up to Buffalo before turning back to the East Coast).

The "reroute" options all propose abandoning the tunnel, either building a nine-mile-long freight tunnel from National Airport to the Deanwood Metro station about 80 feet underground (Concept 8) or building other alignments proposed in recent years by the National Capital Planning Commission (Concepts 9 and 10), or running on CSX's existing tracks out to Ohio and then northward.

But of course, these are concepts, and one of the reasons for going through a NEPA process is to study the different ideas to then come up with alternatives, accompanied by scads of data on noise, vibration, pollution, traffic, and timeline impacts. And to determine how much the various alternatives would cost--because it's likely that CSX is not going to be too gung-ho on the options anticipated to run into the billions of dollars.

It's expected that the public meeting where the alternatives will be unveiled will be in February of 2012, at which point so many of the questions that residents have been asking for so long about how the tunnel construction will affect the day-to-day lives of people who live near and use Virginia Avenue will get some concrete answers.

Faisal Hameed of DDOT, who ran much of the meeting, emphasized a number of times during the Q&A that this is a unique project: a private company is doing work they are paying for themselves on a right of way that they own some (but not all) of, but the impacts on vehicle/pedestrian/bicycle transportation are expected to be extensive enough that DDOT requested this environmental assessment before getting to the point of signing off on any permits that CSX will need to do the work. (There is also apparently still some negotiating going on between CSX and DDOT about exactly whose right of way is where, but it was said that no portion of the project will enter private land, though some small incursions will happen on the Marine bachelor enlisted quarters' site west of 7th Street.)

The Q&A was a pretty peaceful one as these things go (which makes a cranky blogger so very happy!). Most of the wrangling between audience members and CSX was over the route that hazardous materials take when they are forced to go around the District because of various city laws and federal regulations; the audience members were trying to get CSX to admit that there's an existing route bypassing the city that's shorter than anything shown in the concepts, while CSX wasn't going to get anywhere near telling people where hazardous materials travel.

In response to one audience question (coming as a result of the new FAQ posted on the project web site), CSX did say that they are going to "strongly pursue" getting a waiver to stop the currently required blowing of horns anytime a train enters the tunnel, and that they think it should be a "strong possibility" that it can happen, though of course they weren't wanting to commit.

There were also questions that will be better asked when the alternatives are unveiled, about construction staging, safety during construction, noise and vibration impacts, traffic flow, emergency planning, alley access, and what CSX will do to restore or even improve the Virginia Avenue streetscape when construction is finished. (As for any historic preservation impacts, a Section 106 review of the project is being done concurrently with this NEPA assessment.)

Comments are being accepted on these 12 concepts for the next 30 days, either by using the web site or e-mailing contact@virginiaavenuetunnel.com. (About 530 comments were received after the September scoping meeting.) It's hoped the environmental assessment will be completed with a final NEPA decision by the summer of 2012; though, if there is a finding that there will be a "significant environmental impact" from whichever construction alternative is chosen, then a full Environmental Impact Study (EIS) would then have to be done.