I agree, you need to have a bright rear tail light like the Blackburn Mars 4, or the Serfa USL-TL60 The Shield, or the Cygolite HotShot. When a driver is driving in daylight their eyes pupils shrink, upon entering a dark tunnel all they see is black, the end of the tunnel, and any tail lights that may be on, if you don't have a tail light they probably won't see you before they feel you. Your choice, be felt or be seen.