This week's post gets into the "fun stuff" -- specifically, where do we go after Kenmore or Kendall?
There are three major ideas that get thrown around, and which all, in my opinion, are somewhat "crazy" but still "reasonable" enough to distinguish them from (for example) replacing GLX with the Blue Line: Blue to Highland Branch, Blue to B&A, and Blue to Watertown & Waltham. I think all of these have significant merit, and I think all present significant challenges.
I confess that the genesis for this series actually came from wanting to avoid repeating myself regarding the challenges of Blue-to-Riverside, which is probably the most common "crazy transit pitch" I come across. And to be clear, sending the Blue Line to Riverside is itself a solid idea, which has been around since at least 1971, from what I can tell.
What I've tried to illustrate in my post, however, are the knock-on effects of such an extension. To put it perhaps provocatively: "Future Commuter Rail riders in New Bedford would rue the day the Blue Line was extended to Riverside."
On a different note, though I spend a good amount of time outlining why such extensions would be challenging, I personally find an extension to Watertown the most promising, at least on a 100-year timescale. It would require a generation of advocacy. Moreover, I think it is even further down the road than "Phase 2", as I believe that an intermodal West Station, with transfers to circumferential service and regional rail, would itself be a logical "second phase" destination point, in that it would provide valuable service, would still leave options open for the future, and would potentially be a modestly low-impact build.
I believe that
@Charlie_mta has put forth proposals for a largely-elevated ROW between West Station and Watertown Square, and while obviously very expensive, I do think it's a compelling proposal, but again, on a 100-year timescale. I do think building further to Waltham is hard to imagine, in any century. And, as I outline in the post, I believe a better alternative to serve Watertown is a combination of LRT and Regional Rail. I could also envision an elevated extension along the Mass Pike to a major transfer center at Newton Corner; replace the Boston Landing commuter rail station with a Blue Line stop, and then add extra stops at Blue Line-spacing at Market St, Parsons St and Bigelow St, and allow Regional Rail service to run express between Newton Corner and West Station. I like both of these ideas, but I also don't think either of them is a surefire winner. Better to lay the groundwork with extensions to Kenmore or maybe West Station, and add Regional Rail service, and see where that lands us first.
That all being said -- if we want to talk about truly crazy transit pitches, imagine what a Blue-to-LMA extension would set you up for. Kenmore to LMA to Roxbury Crossing to Nubian to Newmarket to Seaport to Logan to Airport to Chelsea to Everett to Wellington. (Yes, I made a map of this, yes, it is ridiculous, yes, I will post it at some point. I named the file "Project Blue Lace", to rhyme with "shoelace" because the Blue Line looping back on itself looks a bit like a shoelace. Yes, I was way too happy with myself for the pun.)