Because Wellington is 20 seconds away?
It's also got the space for it, the land utilization that could be
improved somewhat by trading parking acreage for parking height, and is the superior location for a park-and-ride being on an E-W parkway with fewer traffic lights than any other collector.
The linchpin is going to need to be MassHighway completing the missing legs of the 93/16 interchange by adding:
-- 93N to 16E offramp
-- 16W to 93N onramp off the existing collector road
-- 16W to 93S onramp grafted onto the existing traffic light
. . .and then deleting the Mystic Ave./Exit 30 ramps to clean all that traffic off the city-street section of Mystic Ave.
That's what load-shifts enough extra traffic away from McGrath, Mystic Ave., and Sullivan to start weighting the Wellington Circle light cycles much heavier in the 16/E-W direction and much lighter in the Fellway/N-S direction. Fellsway's the one carrying too much induced demand because of that mangled sequence of 93 interchanges, punishing 16's
natural demand by splitting the Circle light cycles 50/50. Everything would flow much better without queue backups if 16 could grab two-thirds or three-fifths of the cycle.
That helps the park-and-ride situation by giving Wellington a much freer-flowing shot to 93. So now you take the wasteland on the east side of the station and build an equivalent-size garage as the west side of the station, expanded parking capacity from the existing lot at 1/5 the land utilization, placed much closer to the parkway for egress than the narrow maze between parking rows. Give the entire back acreage over to the T for a bus depot and maintenance yard (note: this is exactly what their own bus study was looking at to close Fellsway and Lynn garages and consolidate at a Charlestown/Everett/Medford "main campus").
Now you have a parking sink where a parking sink should ideally go, and it's a fat enough target that casino-goers won't be cruising Sullivan or Assembly looking for spots. The casino shuttles can just run with much heavier headways to Wellington for the folks who want T station parking for a day trip of little casino action + little downtown action.
And then for actual casino traffic down 99...focus on rebuild of the Santilli Circle rotary and
those incomplete ramps from 16 to compact that whole setup into something more logical that involves direct access and a less-distended trip down the frontage road.
Don't worry about increased volumes on the Sullivan end of 99, or more parking at Sullivan...focus on
removing more volumes from that end by smoothing out yet more of the flow kinks on the 16-to-93 segment. This works by:
-- fixing 16/93 interchange
-- fixing 16/99 interchange
-- Fellsway writ-large induced demand reductions to weight Wellington Circle traffic/signals way heavier in the 16 direction
-- Sullivan writ-large induced demand reductions (Rutherford Ave. diet, Square-proper traffic calming, 16 the preferred signed casino route for the out-of-towners, less hunting-and-pecking for parking around there)
-- Wellington upgraded to the parking-sink T stop taking advantage of the 16 upgrades. Again, ending the hunt-and-peck game for parking at other stops. If you've gotta have an Alewife Redux (and they probably do), this is the place for it.
I'd also say, if the EIS'ing isn't too brutal around the back way around the river, the Mystic View Rd. access road to Gateway Center can be upgraded into a casino driveway with an overpass over the train tracks. You'd need 1 traffic light at the primary shopping center driveway, but otherwise the whole of that road from there to Costco and around back to the dam is totally empty. Couldn't they just snake a slightly widened version of it around the back of Costco, cross over the tracks, and be there without ever touching Route 99?
That's -1 rotaries on 16, -4 traffic lights on 99...and
now you can start putting 99 on a road diet too to really discourage over-use of Sullivan. Gateway Ctr. = main casino driveway...full-stop. That, and putting your chips on 16-to-93 as the main conduit and Wellington as the main parking sink is where this traffic all gets reliably funneled onto a preferred corridor. I think the net result ends up significantly
less traffic than today at Sullivan and through all manner of Somerville because of what it further enables for induced demand-control road diets.
