The T planned a Riverside station connecting path on the Lower Falls ROW over those disused 128 rail overpasses. Pitchfork-wielding NIMBY's in the cul-de-sacs by the golf course violently shot it down. Blah-blah-blah "undesireables" blah-blah-blah. It would've linked directly with 16 in Wellesley, which is virtually unwalkable to Riverside or Waban because of the 128 ramps everywhere. And it would've hooked up to the trail on top of the aqueduct that goes all the way to Wellesley Center.
Maybe they can take a second run at this, because it's too useful to pass up and another one of those urban trails that would get commuter utilization like it was its very own transit line. But jeez did that provoke disproportionate histrionics the last time they tried it a couple years ago. I don't think that neighborhood gives a shit about giving itself any access to Riverside station so much as it fancies itself a gated community. If it gets built at all it's got to be strongarmed for the sake of the Riverside development. It will never ever get voluntary cooperation from the abutters.
In an attempt to defend the neighborhood were I grew up and lived for 18 years against your charges of being a "gated community" (it isn't and doesn't want to be any more than any other neighborhood does), here's the actual, ongoing story of that path.
First off, it isn't the T that's trying to build it. It's the DCR, who owns the ROW, that wants to build a mixed-use trail between Riverside and Route 16, and it has nothing to do with making Riverside more accessible or creating a "transit-like" piece of infrastructure. DCR sees that ROW as a necessary segment of their recreational path along the Charles River. They hope to one day connect that section to Waltham and Watertown by building additional segments in Auburndale, but this is their first step.
It's not really the case either that they made an attempt to build it and were rebuffed. They proposed it about five years ago and split the neighborhood between the folks who lived directly abutting the tracks (and thus would have the path right behind their yards) and those who lived further away and valued the easier access to both Riverside and, more importantly, the shops on Wellesley side of the river. That section of the path, BTW, was completed about a year ago in conjunction with the CVS and elderly housing on the Grossman's site, bringing many of the greater plan's benefits without disturbing too many families.
The rest of the project has fallen out of the headlines, but that doesn't mean it's over or that it was angrily shouted down. As my parents recall it, the public meeting with the DCR guy basically amounted to him saying "look, it's my land, and I'm going to do this. You can work with me on it or you can get screwed." Predictably, the abutters called him on the only part he left open to them and sued the state over some obscure abandonment law, basically claiming that the state had ceded them the ROW through 50 years of disuse. I believe that lawsuit is still pending on the central segment of the ROW, which is why no construction has occurred beyond Concord St.
I've heard whispers that DCR will complete the connection over the highway and into the neighborhood using the Clearwater Rd. extension (clearly visible on Google but not in real life) to give Lower Falls bike/ped Riverside access without building behind people's houses. That's a decent stopgap for a project which really is an incremental thing.
There's no "second run" or "strongarming" needed here. What's needed is to make the case, patiently and consistently, that Lower Falls existing on a dumbbell of commercial development with one end in Wellesley and the other at Riverside is good for property values and convenient for residents. Not only does it allow easier access to run errands and eat out, but it would connect directly to Wellesley's municipal system of scenic paths as well as a (hopefully) rehabilitated Riverside Park and its system of trails. It would be a beautiful walk and a huge boost to the neighborhood.
The bridge is already quite popular (and gorgeous at all times of year). Half the neighborhood already supports the rest of the project. Folks who back up to the path need convincing that they'll end up seeing it as an amenity rather than as an invasion of their privacy, and that takes time. The momentum's on DCR's side, now, though. It will ultimately happen.
By the way, the woods through which the path would run (and Riverside Park to which it would connect) are constantly occupied by the homeless and host unsavory activities in their current, neglected state. I walked the tracks many times as a child and saw the evidence myself. It's not the people who ride the train that folks in Lower Falls are worried about having access to their back gates.