We had a long discussion about this on another thread about two weeks ago. According to the stuff I found and others cite as well, you are about 2X more at risk on the sidewalk as on the road. The reason is that driveways and at intersections, moving cars are not looking for a fast mover like a bike. Just almost happened to me today, I was riding on a sidewalk, too lazy to walk my bike to the intersection, and almost got taken out by a car coming out of a parking ramp.
If the road is super busy and you ate not comfortable on it, find a different road if at all possible.
J.