I found this posting on Planetizen by Micheal Lydon about bike networks an excellent way to assign proper bike usage to different paths and ways:
A proper bicycle network is comprised of four basic types of bikeways: bicycle lanes, bicycle boulevards, shared streets and off-street paths. Although bicycle use is not common in many American cities, planners and government officials must acknowledge that such activity is unlikely to increase without a sufficient bicycle network in place. Cities and towns interested in developing or expanding their bicycle network must consider plans that include all four types. Doing so creates a tapestry of options for the three types of bicyclists and their individual requirements (outlined in my previous post). Portland, Oregon and Berkeley, California experience some of the highest bicycle mode shares in the country precisely because they use a layered approach. Before continuing, it's important to loosely define each bikeway type.
Not only is this post a great way to approach the planning of a bike network, Lydon also realizes that there has to be an order and hierarchy in the planning process:
Though traffic engineers and many transportation planners are notorious for their myopic auto-centrism, this does not discount the same narrow scope respective to alternative transportation advocates, architects or environmental planners. Although this trend cannot be overcome simply through the discipline of bikeway planning, I would recommend that those involved with bicycle facility design assign priority in the following order:
3) Motor Vehicles
Recognizing this hierarchy means that bicycle facilities should not trump the pedestrian experience.
I like this approach and if we are serious about bike planning, just like the traffic engineers are serious about traffic, we need to have a systematic way to categorize every possible bike pathway. Check out the rest of Lydon's posts here.