(https://i.imgur.com/lYibOQR.png)
Boston's expressway system neatly resembles a spoked wheel with 2 beltways, 128 and 495, and several radials connecting them. There is just one, or rather two, gaping holes in this neat symmetry. North of Boston, there are 3 radials, MA 3, I-93, and I-95, and south, there are also 3, I-95, 24, and US 3. But west of Boston, there is only one radial, the Masspike.
I'm not the only one who has noticed this gap. Back in the 60s and 70s, the MassDOT planned on filling them in. Route 2 was to be made into an expressway and a new expressway, called 209, was to plow through the dense forests between Westwood and Milford. They even wanted to extend 290 to Waltham, for those of us who don't like paying tolls.
(https://i.imgur.com/eukdL3F.jpg)
But none of this happened, although the Route 2 expressway might happen if the state ever found funding, recently they upgraded one of the 9 at-grade intersections, Crosby's Corner in Lincoln, into an interchange.
You might say this is NIMBYism, but how come they couldn't stop the freeways South or North of 128?
- More population north and south than west...especially south as you had both the coast and along the old Post Road to Providence (i.e. US 1).
- 93 and 95 are Interstate highways, so you had Federal inertia there.
- Possibly because of the population distribution, the corridors north and south were prioritized. Except for 95 where it parallels 1 in Danvers and Peabody, the corridors north and south of 128 were all completed by 1970. Keep in mind that the early '70s was when the freeway revolts peaked in Boston. You also had inflation eating into highway dollars through the '70s, plus the oil embargoes of 1973 and 1979, so that all likely played a factor in the remaining corridors (especially outside of 128) not getting built.
Unrelated: You're not seeing things, the MassDOT wanted to build another beltway between 495 and 128. Almost no mention of it is made outside of the study where this map came from, so I guess this was just another example of highway planners throwing lines on maps to see what stuck.
But something fun to think about is Boston would have 5 beltways if they had gotten their way. Outside of 495, I-190 would be extended to Manchester, creating a continuous semicircle freeway from Hampton, NH to Wareham, MA. And I don't think there's anything more to say about the Inner Belt.
I feel a certain pride that we in Wellesley were generous enough to allow our town to be bifurcated by Route 9, even though we could have easily gotten it cancelled. But those guys in Dover and Weston couldn't sacrifice even a tiny bit of land for the greater good of the region.