To avoid being squashed:
- Always leave the bike in first gear while you're stopped at an intersection.
- Watch your mirrors to keep someone from ramming you from behind.
- Stay to one side or the other of the car ahead of you. It gives you somewhere to go if you must make a quick exit.
- If you're in California, lanesplit. The drunk coming up from behind can't hit you if you're between two other cars. But even then, still pay attention to items # 1 & 2 and get the heck out of Dodge before any impact.
- Run yellow lights (usually). See Approaching an intersection
- Work on developing your situational awareness: Know exactly where all the traffic around you is located, and constantly update your mental map of where they will (or MIGHT) be in the next few seconds. The only real defense a biker has in a bike-vs-cage collision is not to be there when it happens.