My question is, what happens to the traffic that uses those ramps?
The proposal is to close the most redundant fraction of an exit and build the most transformative mass transit project this region has seen in over a lifetime, if ever.
As for what happens to the trips currently using those ramps, that depends on the trip/person. Some options include: Exit 15B, Exit 16B, Exit 17, the unnumbered Chinatown on-ramp, Commuter Rail to South Station, Amtrak to South Station. Every one of those options is less than a quarter mile from the aforementioned ramps.
I chose the ramps I did because they have the most redundancy with nearby ramps and are steering traffic onto streets that should not give priority to automobiles. This idea that somehow no exit can be eliminated misses the fact that we already see it successfully done locally, domestically, and internationally all the time!
Do we need some automobile access downtown? Of course.
Do we need exits and entrances to the Central Artery Tunnel to/from Downtown Boston? Probably for the time being.
Would our urban core be improved by massively increasing mass transit capacity and slightly limiting the flow of automobiles into our urban core? Of course!