It'll only cut down on traffic if all the new arrivals in Boston do not use cars and many older Boston residents also give up their cars. Fundamentally, transit is an investment into infrastructure that has better scaling properties than car-centric development. It's there to absorb further growth in the region.

You don't need to give up the car - you just need to reduce car trips.

The easiest way to do that is reduce commuting trips, as those are very common, but you can reduce trips in other ways, such as allowing more gas stations/convenience stores. If it's a five minute drive to the grocery store but a two minute walk to a 7-11, some of those trips to the grocery store will be replaced with walks to the 7-11.

By "do not use cars" I meant replace car trips via walking or transit.

I don't have numbers, but I can tell you that the city government is serious about providing other alternatives to cars. For example, making buses free. [1]

[1] https://www.boston.gov/news/new-steps-reduce-vehicle-emissio...

The buses aren’t generally free though: https://www.mbta.com/fares/bus-fares

They are free on only 3 lines (plus SL1 leaving the airport) https://www.boston.gov/news/mayor-wu-takes-steps-expand-fare...

Free buses should not be considered in any city. Spend that money on more frequent routes. People will not use a free bus that only comes once an hour, or doesn't stop close to them. Until your city is covered with transit coming every 5 minutes you need to work on that not cost.

Not even the best transit cities have transit every 5 minutes all over the city. There is a lot of room to improve in them all

Traffic is worse than it ever was. I basically avoid going in for activities any longer. Which is fine. But it's mostly not worth going in to meet people in the city in the evening at this point.

Try taking the bus next time.

I actually live near commuter rail and will generally take a 90-120 minute total drive + train ride (every hour at most) + subway in for a 9-5 event. It makes zero sense for an evening event. I'll somewhat reluctantly do the 90 minute drive in and hour drive home now and then to go to the theater or some other thing I really want to do.

So it's not as simple as take the bus. But that's fine. I mostly just don't go in.

The goal isn't to reduce traffic but to increase mobility.

That's good, but the context of this thread is redesigning urban areas to encourage reducing car traffic.

The ultimate goal is not to reduce "traffic" (however you define it), the goal is to produce dense, livable cities that don't require car ownership in order to live. The reduction in car-related negative externalities is merely one happy side effect of this.

The bike lanes mentioned above all, by physical necessity, come at the expense of cars, either by reducing parking lanes or reducing driving lanes. Even if there were the same amount of traffic, fewer cars would be on the road because there is less road to be on.