Car accident help, fault?

My husband was on a dark highway, a road he has travelled every night for 3 years. He came up to a stop light and began to slow down, it turned green so he sped back up.( there was no vehicles at the stop light, or anywhere around ) he looked down at his spedometer coming up to the light, looked up, a few seconds later, almost right after the stop light, he saw the outline of a big truck ( he believes it was a black dump truck that was either stopped or going extremly slow, he saw no lights) he hit his brakes but was to close to do any good.He hit it going 55 (not speeding) He was ticketed for careless driving, shattered his femur,broke 2 bones in his foot and bruised a lung.The car was totaled and we only had liability (work car) I guess I am wondering how we can find out if the truck is at fault. lights not on? stopped on the highway?ect..Does anyone have experience with this situation? It just doesnt seem right.