X-Plane 8.50 does all sorts of new things – the picture on the left illustrates “transparent” runways. A transparent runway draws no pavement and does not affect the physics model. But it does have all of the runway lights, signs, and shoulders (if desired).
The purpose of transparent runways is to allow custom scenery to use X-Plane’s built-in approach and runway lights while providing your own runway, perhaps via an object with a hard surface.
Technically you could build your own approach and runway lights by hand-placing light objects (from the 850 light library package) onto your runway, but using a transparent runway is a lot easier and probably more reliable in the long-term.