This rule of the week allows you to create elevated rail guideways. You can create these in CityEngine using a graph, and in this example I show how you can make them coincident with your streets. I use the rail guideway rule from the Redlands Example for lines at grade, and the linked elevated guideway below for lines above grade.
This week's rule allows you to create 3D volumetric representation of camera views. You can customize the view distance from the camera, and set the ratio between horizontal and vertical view field angle. You can control the transparency and color of the view volume, and change the angle and azimuth it points in.