Vehicles ahead of you may stop for pedestrians crossing the street. This is a very common rear-end crash. Watch for pedestrians in all directions before making a turn at an intersection. Also, keep an eye out for cyclists going straight through the intersection, either on your right or on the sidewalk. Don't adjust your radio or stereo, dial your cell phone or be distracted by other things when entering an intersection.
Inattention is a common cause of crashes.
If vehicles are stopped at an intersection with no signs, use extra caution when approaching them. They are usually stopped for a good reason. You never know when the person ahead may turn or stop when approaching an intersection. Tailgating behind large trucks is especially hazardous. You can't see around them, nor can you see traffic signals ahead.