Almost everyone agrees on defining the Level of Service (LOS) as a good measure, however, California is replacing this LOS for Vehicle Miles Traveled (VMT). Under the LOS system, a proposed bike lane had to analyse its transportation impacts and if it was found to slow down cars (by, say substituting a bike lane for a car lane) then the California's environmental statute would have said let’s either not build this project, or pay a lot of money to find some other way to speed up cars.
However, it is in New York where they don't mention LOS and they still state that protected bike lanes released by the New York City Department of Transportation offers a great example of how rider safety can be increased even while car speed is maintained.
So what happened here to overcome the traditional idea that bike lanes lead to car delay? No doubt many factors were involved, but the steady traffic flow was largely the result of adding left-turn pockets. In the old street configurations, cars turned left from a general traffic lane; in the new one, they merged into a left-turn slot beside the protected bike lane. This design has two key advantages: first, traffic doesn't have to slow down until the left turn is complete, and second, drivers have an easier time seeing bike riders coming up beside them.