LOW TIME PLT WAS LED INTO A HVY WX SITUATION AT NIGHT BY A WX BRIEFING THAT DID NOT FULLY COVER ALL OF THE POSSIBILITIES. WHEN HE WAS TRAPPED IN HVY RAIN AT NIGHT; HE LANDED SAFELY ON AN INTERSTATE HIGHWAY WITH NO INJURIES OR DAMAGE.

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I DEPARTED BULLHEAD/LAUGHLIN ARPT FOR LAS VEGAS AT XA00 AFTER A 4 HR DELAY BECAUSE OF SEVERE WX IN LAS VEGAS. I RECEIVED A WX BRIEFING JUST BEFORE DEP; AND SEVERAL BRIEFINGS IN PAST HRS. WX IN LAS VEGAS WAS 4000 SCATTERED; 8000 SCATTERED; 18000 OVCST; TEMP 54; DEWPOINT 48; VISIBILITY 10; LIGHT RAIN SHOWERS. FORECAST FOR WIDELY SCATTERED TSTMS AND RAIN SHOWERS. AFTER DEPARTING BULLHEAD CITY I NOTICED SOME BAD LOOKING WX AROUND THE LAKE MEAD AREA; WHICH IS THE WAY WE HAD TO GO. SO I DECIDED TO CHOOSE AN ALTERNATE RTE. AFTER LOOKING AT MY SECTIONAL; I DECIDED TO TRACK TO THE GOFFS VOR AND THEN TO INTERSTATE 15; THEN TRACK THE FREEWAY TO LAS VEGAS. THE WX LOOKED VERY FAVORABLE THIS DIRECTION. EVERYTHING WAS VERY SMOOTH AND FINE ALL THE WAY TO THE STATELINE CASINO AREA. THIS IS WHERE WE ENCOUNTERED SOME LIGHT RAIN SHOWERS; WHICH I DID NOT SEE AS A BIG FACTOR BECAUSE I'VE ENCOUNTERED RAIN MANY TIMES BEFORE. AS WE CONTINUED TO THE JEAN AREA; THE RAIN SUDDENLY INTENSIFIED TO VERY SEVERE ALONG WITH VERY SEVERE WIND AND TURB. I HAD ALL I COULD DO TO KEEP THE AIRPLANE UNDER CTL. THEN VISIBILITY WENT TO 0 ALL OF A SUDDEN. I GOT ON THE INSTS AND QUICKLY DSNDED TO VFR CONDITIONS AND DECIDED I HAD TO LAND OR WE WERE GOING TO BE IN TROUBLE. I HAD THOUGHT ABOUT DOING A 180 DEG AND GOING TO JEAN ARPT; BUT IT WAS NIGHTTIME AND THE ARPT IS UNLIT AND A GRAVEL RWY; SO I DEEMED IT UNSAFE. I KNEW THE FREEWAY WAS RIGHT BELOW AND COULD BE EASILY REACHED; SO I DECIDED TO LAND THERE. I LANDED WITH TFC AND PULLED THE AIRPLANE OFF TO THE SIDE OF THE ROAD. A TRUCK DRIVER PULLED OVER TO HELP US. WE WERE NOT HURT NOR WAS THE AIRPLANE OR ANY PROPERTY OR OTHER PERSONS. I BELIEVE THIS UNINTENTIONAL SITUATION COULD HAVE BEEN PREVENTED BY NOT GOING (STAYING OVERNIGHT IN LAUGHLIN) OR TALKING TO CTR OR FLT SVC IN THE AIR TO SEE WHERE WX WAS. THIS SITUATION WAS TOTALLY UNEXPECTED; BUT LUCKILY IT TURNED OUT SAFELY. I THANK THE EMER TRAINING AND TRAINING FOR MY INST RATING I'VE HAD SO FAR; IT HELPED ME STAY IN CTL AND NOT LET THE SUDDEN FEAR TURN TO SUDDEN PANIC.