Imagine you are driving down the road as you have so many times before. You've always been a healthy person your entire life -- but on this day, you suddenly feel pain in your chest. You hope that the sensation goes away, but it only gets worse as time goes on. Within moments, you are unable to operate your vehicle safely and you get into an accident. The medical emergency you suffered directly contributed to this wreck.
When a truck collides with a smaller vehicle, it is highly likely that the smaller vehicle will suffer the most damage and that the people inside that vehicle will suffer the worst injuries. This is simply due to the inherent nature of larger trucks. They carry more weight and thus maintain their momentum far easier than smaller vehicles. They also make a greater impact when they collide with any object.