This is someone else’s work; I just saw it and thought it made a tremendous amount of sense.
The motivation is:
Mass Ave in Cambridge devotes far more space than necessary to automobile traffic, based on existing car counts, and is too dangerous for many people to bike, and traffic jams there impede transit.
The proposed change is to replace the current configuration with (one edge to middle)
sidewalk, bike lane, parking, car lane, bus lane
so bikes are protected by parking, and buses run unimpeded down the middle.
One lane each way is adequate for the current car traffic — which won’t be impeded by stopping buses — and buses won’t be impeded by lines of stopped cars.
For a bus stop, the parking is removed, the car lane will chicane into the space where parking would be, and a boarding area is provided for bus access.
The bus lane is available for emergency vehicles and to allow cars to get around obstacles in their lane (like parking cars or “just for a minute” stops).
Note that the improved bus speeds might allow us to re-route some of the other buses, for example the 62 and 350 from Lexington and Burlington, into Cambridge so that drivers from further out might have other, simpler options (bus priority through the Route 2/Parkway mess would help here) which could relieve some of the pressure for car traffic. This ought to also provide substantially better routes for biking; I bike in to Kendall Square every day, but I stay off Mass Ave because I don’t think it’s safe enough.
I don’t know if something like this might have been possible for Trapelo Road, but that opportunity is gone for a long while.
The main problem to watch for here is turning traffic not giving way to either bikes or buses.
It might be interesting to look into traffic-detector-driven signals that would help mitigate this risk; for example a pair of lights, one for bike, the other for car, indicating (to the bike) “you have been detected” and to the car “a bike is detected, turn with extreme care”.