ROAD DEFECT ON BRIDGE ON I-70 WHERE IT CROSSES I-270 JUST WEST OF ST. LOUIS, MO. DRIVING IN THE RAIN WE HIT A METAL JOINT THAT RUNS LENGTHWISE WITH THE BRIDGE IN THE RIGHT TIRE GROOVE OF THE LEFT HAND LANE. BEING RECESSED INTO THE ROAD, BEING METAL, AND NOT VISIBLE UNTIL WITHIN ABOUT 40 FEET OF THE OBJECT, IT IS NEARLY IMPOSSIBLE TO MISS AND IN OUR CASE RETAIN CONTROL OF A MOTORCYCLE WHEN IT IS RAINING. JUST SOME APPROPRIATE SIGNAGE WOULD HAVE PREVENTED THIS ACCIDENT. THE TOWING COMPANY TOLD ME THAT THERE ARE MANY MOTORCYCLE CRASHES AT THIS LOCATION EVERY TIME IT RAINS. I CERTAINLY WOULD LIKE TO KEEP SOMEONE ELSE FROM HAVING THE SAME RESULTS AS WE DID. THANK YOU *AK