I was stopped in traffic when i was rear ended by a driver doing approximately 50 mph on a 3 lane parkway, which caused me to crash into the car right in front of me. the collision was violent enough to cause bruising on my bicep and upper thighs and knocked my hearing aids onto the dash. the airbag did not deploy and the seat belt inertial reel did not activate properly as my head was above the steering wheel when it finally caught. i do not know if the seatbelt reached the end of its length, or the inertial reel finally locked, but when it did stop me, the lap belt was on my upper things, the shoulder strap was down across my arm and stomach and my head was up over the steering wheel headed for the front window. i believe this exacerbated my lower back injury by causing a severe twisting moment as opposed to being restrained properly in the seat.