A movable jersey wall in Vancouver protects simply and quickly.
Parked cars, door zones, plastic hit posts, potted plants, curbs, bioswales. What do all of these things have in common? They are all methods to protect bike lanes from moving cars. Some of these methods are quicker to implement than others. Plastic hit posts are perhaps the quickest to implement and would reduce, though not prevent cars from entering bike lanes. They are cheap, easy to replace, but provide the least amount of protection.
Philadelphia routinely ranks highest of the 10 biggest US cities for bike commuting, and ridership in the neighborhoods around Center and South Philly is right up there with superstar bike cities like Portland and Minneapolis. But the city's bike friendliness has a lot more to do with the built environment we've inherited than anything modern day city leaders have done for cyclists.