All good ideas, but you still have the basic problem that the development is isolated from even the most mundane retail services, such as a convenience store or a drugstore or a Dunkin Donuts.
It'd be easier if there was an actual footpath from Alewife station to the shopping mall instead of having to cross the street. That would significantly de-isolate the area. As is, people have worn their own footpath "ramp" down the hillside from the bridge so mall access and Danehy Park are at least imperfectly closer to Alewife and Rindge Ave. They prop a shopping cart on the retaining wall at the bottom to jump down rather than walk a couple hundred feet more to the driveway. Kids especially use this to get to Danehy Park to avoid the ridiculous Sherman St. end-run. You would think after all these years of this DIY practice that somebody would take the hint that this is an unequivocal expression of demand for a ramp on that side.
Second would be to get an actual grade-separated path from Alewife across the tracks to avoid having to cross the parkway at all. And then re-do the parking lot asphalt wasteland on the northwest corner so you can actually reach the stores, cinema, and Danehy Park without getting killed by cars swerving around ineffective speed bumps for their own personal 50 MPH expressway bypass around the Fresh Pond rotaries.
Why can't they do something like this:
Initial Build
-- Landscape a sidewalk all the way from the Alewife driveway/Cambridgepark Dr. intersection, along the back of the Summer Shack driveway, and curving under the bridge. The space under the bridge is used for nothing except Cambridge DPW storing palettes of sidewalk bricks.
-- Put a footbridge over the tracks to where Terminal Rd. meets the Mall parking lot.
-- Re-landscape the parking lot so there's actual medians w/sidewalk for traversing the distance to the stores, movie theater, and rear exit to Danehy Park and the just-built New St. condos without getting squashed. Separate parking spaces from egress to calm the incredibly dangerous speeds across the lot from Terminal Rd. to New St.. Sort of like the renovated Assembly Square plaza lot, but with better sidewalks through the lot. Plant a few trees on these medians to make it look like less a trash-windswept moonscape.
-- Put an ACTUAL ramp up to the parkway where that DIY footpath is so bicyclists, the handicapped, kids, and people pushing strollers can get to the other side of the parkway from Alewife without needing to cross at Rindge Ave. Rindge isn't a terribly unsafe intersection because of the two shortish-cycle traffic lights in quick succession and the ramps from the station exits on each side. But the parkway is still psychologically daunting to cross and physically isolating. Especially for all the small kids in the area.
Related Gap-filler (de-isolating Alewife with infill links):
-- Redo the sidewalks on Terminal Rd. for ped friendliness where the no-longer-DIY hillside path and the footbridge over the tracks meet. Put in a bike lane on Terminal...car speeds aren't that bad on it because of the curves. Now the renovated plaza across the street and 185 Alewife are actually pedestrian/bike accessible too and not half a world away from Rindge Ave. or the mall directly across the street.
-- Stick a path BEHIND the plaza where there's currently just a couple employee parking spots and fenced-off dumpsters to link the Concord Ave./reservoir pedestrian light and those isolated condos on Wheeler St. to Alewife in grade-separated fashion. Do ped-friendlier sidewalks and a bike path on Wheeler just like on Terminal. Now you actually have a contiguous path from the Minuteman system to the Fresh Pond paths and fill in the pointless 1/4 mile gap in the path system. It's incredibly dangerous for the bicyclists who are pretty much S.O.L. through the gap, and while the sidewalks on the parkway are wide and safe pedestrians psychologically avoid them because of the cars screaming by. They cut through the plaza parking lot and dodge cars clumsily moving around the poor lot layout, which ends up being even more dangerous. This removes the last safety and psychological barrier to linking all the paths, parks, and development on the parkway.
-- Put a stub sidewalk from the tracks footbridge down to the Rindge Ave. apartments so there's access from there. Now the kids can get safely from the DCR park to Danehy Park without making a ridiculous end run to Sherman St. or climbing down the hillside and playing human Frogger in the parking lot expressway. And can finally get to Fresh Pond.
Other Future Considerations:
-- The decrepit Watertown Branch freight railroad has a path planned on the abandoned East Watertown portion linking the neighborhood to the Charles paths and eventually Watertown Square with Watertown Mall. Pan Am Railways is involved in a protracted dispute with the last customer on the line to abandon the rest of it all the way to Danehy Park where it junctions with the Fitchburg Line. The path would then be extended from East Watertown to Fresh Pond. Pan Am will eventually settle with that customer, and Cambridge and Watertown are chomping at the bit to complete this link because it'll get HUGE utilization (probably rivaling the Minuteman). This is a big reason why it would be insane to not fill that 1/4 gap between Alewife/Minuteman/Davis path and Fresh Pond.
-- Porter Square path. The Fitchburg line in ancient times had 4 tracks on it all the way out to Waltham, which is why they're able to fit the Green Line extension to Union Sq. on its existing footprint. If you look out Alewife way from the Porter overpass or any other streets you'll see how fricking wide it is...so wide that there's a fence at Sherman St. to keep people from joyriding cars and ATV's off-road next to the tracks. It's a de facto shortcut to Danehy Park and the mall anyway, as people just walk up the Watertown Branch split (vagrants have even ripped up the fence on the swampy corner of Danehy to get in). There is also, underneath the Walden St. bridge, a historic brick arch tunnel that used to be used in the 19th century to herd cattle from slaughterhouses near Porter for loading at the old Alewife rail yard. This tunnel was painstakingly restored when they rebuilt the Walden St. bridge because it's on the Historic Register. It's totally unused, though. Throw down a path from the footbridge/Rindge apartments access all the way to Porter rail-with-trail style, with proper fencing. Link with the commuter rail stairs, throw down sidewalk a ramp at the nicely renovated Walden Sq. Apartments pedestrian underpass. Now you've linked the apartment blocks on Sherman, two city schools, playgrounds, and Porter Shopping Center to Alewife with nothing but a simple pave job and chain-link fence.
With road options so limited, I really think a build-out of the path system like this is the only way to stitch together all that poorly designed odds-and-sods development around Alewife so they're actually somewhat connected to Cambridge via non-intimidating means. I think it's the only way the city can half-justify its hellbent desire to make lemonade out of a development lemon of a location. A couple of those access projects like the Alewife-Fresh Pond path infill and re-do of the mall parking lot for non-deadly pedestrian access to retail and Danehy Park are years overdue unto themselves for strictly safety reasons.
