Those 3-1/2 ft. are not fit to be called a sidewalk.
It doesn’t have to be this way.
The topic of our discussion is Braeland Ave., a one-way street on the south side of the Newton Centre T stop. There’s plenty of street width (28 ft.) for a protected passage for pedestrians (say that 3 times fast!), a bike lane (or more), the existing parking, and a vehicle lane.
Imagine the tree on the left is on a hill down to the tracks. There’s the fence, the 3-1/2 ft. not-really-a-sidewalk, a parking lane, and a huge travel lane. Among other things, such a huge travel lane encourages speeding.
To provide a safer walk for pedestrians you would, ideally, update and widen the sidewalk. But, that costs big money and requires planning and design. For relatively short money (in the thousands), you could divide the road with paint and reap huge benefits.
Move the parking over five feet to create the pedestrian passage, protected by the parking. Add a nice, safe, six-foot bike lane on the other side. That leaves ten feet for a travel lane, absolutely sufficient for a street like Braeland Ave. Importantly, folks who live on the south side (right) would have plenty of room (16 ft.) to get in and out of their driveways. And narrowing the travel lane (physically with the parked cars and with the painted bike lane) would almost certainly reduce speed.
Given the volume of traffic on the street, that would probably provide the maximum, safe bike accommodation you can create with paint. (As with the sidewalk, the ideal bike solution would be some sort of separated bike facility.)
While we’re at it, why is the parking along here free? (There are meters on the first few spaces off Langley.) Now that the city has Parking Passport, we can charge for these spaces without adding meters or a kiosk. (Yes, I’m suggesting that, during the period of paid parking, these spaces would only be available to people with smart phones.)
Bottom line: there’s just no good reason to make people walk in the street.