Bicycle route planning, break it down to systems

[B' Spokes: I like this idea of having bike routes with different purposes, though I might add to these concepts with recreational routes (loops.) Baltimore has Lake Montebello and Druid Lake, NYC has Central Park and Prospect Park.]
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Excerpt from Chicago Streets for Cycling Plan 2020

This proposed 645-mile bicycle system will run throughout Chicago’s neighborhoods. The overall system consists of three smaller systems: Neighborhood Bike Routes that utilize residential streets, Crosstown Bike Routes that use collector and arterial roadways, and Spoke Routes that connect all corners of the City to Downtown. Once the network is complete, all Chicagoans will be within 1⁄2 mile of a bicycle facility.

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<a href="http://www.chicagobikes.org/pdf/2012%20Projects/ChicagoStreetsforCycling2020.pdf">http://www.chicagobikes.org/pdf/2012%20Projects/ChicagoStreetsforCycling2020.pdf</a>;