I think the pink line are victor airways. These are low altitude routes. The blue lines are Jet routes. These are high altitude routes.
Here is a site that talks about the different charts.
http://www.navfltsm.addr.com/vfrcharts.htmIntersections are points in the sky where two or more airways meet. Like the intersections of a road. The air routes were created to keep air traffic seperated. The work just like the roads, only in altitudes. These all radiate out from VOR stations.
If you are flying VFR on an airway you are going to want to be at odd altitudes plus 500 going east (360-180), and even plus 500 going west (180 - 360). If you are IFR then you are at the same altitudes without the extra 500 feet. Really pretty interesting trying to navigate like the real world aircraft in FS9.
