Try drawing edges over the terrain that will relate to the centerline of the road (with the terrain in a separate group so it won't interact. Use the center line as a guide to use follow me on a profile of your street and sidewalk. The number of edges you use in the center line and whether or not you adjust it to finesse the road grade and curves determines the quality of the road to some extent. You may want to use follow me and keep or upright extruder plugins. Use Sandbox drape to adjust the terrain to the road since google terrain does not conform to any road, real or imagined. Drape gives vertical or uniform slope cuts---you can increase the offset to get more gradual cuts but the offset is the same all sides, unlike real roads. You may wish to sculpt the terrain afterwards---or include ample apron in the road profile to fit to the terrain better. This is one way using basic tools. A little rough but you wanted "simple". Keep searching this site there's more evolved methods discussed in the forum.
You can see in the example that I did not use many edges and there will be abrupt surprises for the drivers on this road. You can use plugins like Bezier Spline and Curvizard to manipulate your center line.
Screen Shot 2015-08-15 at 6.14.47 PM.png
