DURING A HEAVY RAIN STORM A TRACTOR TRAILER IN FRONT OF ME SLOWED TO PULL OFF THE ROAD. I COULD NOT SEE HIS BRAKE LIGHTS BECAUSE OF THE RAIN AND REAR ENDED HIM. THE IMPACT WAS STRONG ENOUGH TO BREAK HIS BUMPER BAR OFF (THE PART THAT HANGS DOWN FROM THE ACTUAL BED OF THE TRAILER TO PREVENT YOU FROM GOING BENEATH IT). THERE ARE CLEAR MARKS ON MY FRONT BUMPER WHERE HIS BUMPER HIT. MY AIRBAG DID NOT DEPLOY. I ESTIMATE MY SPEED WAS ABOUT 40MPH ALTHOUGH I SKIDDED INTO HIM SO I WAS SLOWING. I DON'T BELIEVE THAT HE WAS STOPPED BUT WAS MOVING SLOWLY AS HE PULLED OVER. I DONT KNOW HOW OFTEN THIS OCCURS, ONCE WAS ENOUGH FOR ME. MY VEHICLE IS A TOTAL LOSS SO NO ACTION IS BEING TAKEN TO CORRECT THE FAILURE. *TR