THE SAMPLING PLAN, CONSIDERING ROAD SAFETY FACTORS, INVOLVED THE DEVELOPMENT OF A REFERENCE GRID FOR EACH OF FIVE RESEARCH AREAS OF THE COUNTRY AND THE DIVISION OF THE AREAS INTO SQUARES WITH SIDES OF A CERTAIN LENGTH. THREE DIFFERENT PRINCIPLES WERE USED IN SAMPLING VEHICLES: ALL PASSING VEHICLES WERE CONTROLLED; VEHICLES WERE STOPPED AND CONTROLLED IN ACCORDANCE WITH AVAILABLE RESOURCES; AND EVERY SECOND, THIRD, ETC., VEHICLE WAS CONTROLLED, WITH THE CONTROLLED PROPORTION DECIDED IN ADVANCE OF THE BASIS OF TRAFFIC FLOW INTENSITY. A TOTAL OF 9,125 DRIVERS WERE CONTROLLED DURING THE TEST PERIOD. IT WAS ASSUMED THAT THE PROPORTION OF DRIVERS UNDER THE INFLUENCE OF ALCOHOL VARIED FOR DIFFERENT TYPES OF ROADS. THE CONTROLLED ROAD SECTION, THEREFORE, WAS DIVIDED INTO FOUR DIFFERENT CATEGORIES: ROAD OR STREET WITH A CONURBATION AREA AND ITS SURROUNDINGS, INTERNATIONAL MAIN ROAD, NATIONAL MAIN ROAD, AND COUNTY ROAD. IT WAS ASSUMED FURTHER THAT THE PROPORTION OF DRIVERS UNDER THE INFLUENCE OF ALCOHOL VARIED DURING THE DIFFERENT HOURS OF THE DAY AND NIGHT, AS WELL AS DURING DIFFERENT DAYS OF THE WEEK. A POSITIVE TEST FOR CONTROLLED DRIVERS MEANT THAT THE BREATHING AMPOULE SHOWED MORE THAN 0.5 PRO MILLE. A NEGATIVE TEST COULD INDICATE THE INFLUENCE OF ALCOHOL BUT NOT ABOVE 0.5 PRO MILLE. TESTS WERE POSITIVE FOR 24 PER 1,000 DRIVERS AND NEGATIVE FOR 42 PER 1,000 DRIVERS. DIFFERENCES AMONG DRIVERS IN TERMS OF CONURBATION AREAS AND COUNTY ROADS ON THE ONE HAND AND INTERNATIONAL AND NATIONAL MAIN ROADS ON THE OTHER HAND WERE MARKED. DATA WERE NOT SUFFICIENT TO BE ANALYZED IN RELATION TO DIFFERENT INTERVALS OF TIME. FOUR GENERAL CONCLUSIONS WERE REACHED BASED ON THE NUMBER OF DRIVING OCCASIONS, THE STRUCTURE OF THE ROAD NETWORK, AND THE NUMBER OF VEHICLES AND DRIVERS IN AREAS DURING THE INVESTIGATION: (1) THE NUMBER OF DRIVING OCCASIONS UNDER THE INFLUENCE OF ALCOHOL AND PUNISHABLE BY LAW WAS NOT BELOW 100,000; (2) TOTAL TRAFFIC WORK UNDER THE INFLUENCE OF ALCOHOL DID NOT INVOLVE LESS THAN 700,000 KILOMETERS; (3) THE MAJORITY OF DRIVING OCCASIONS UNDER THE INFLUENCE OF ALCOHOL TOOK PLACE ON ROADS OR STREETS IN CONURBATION AREAS AND ON COUNTY ROADS; AND (4) DRUNKEN DRIVING WAS GENERALLY MORE TYPICAL ON WEEKENDS. THE POSSIBILITY OF GENERALIZING THE FINDINGS IS LIMITED BECAUSE OF THE SMALL SAMPLE SIZE AND THE INABILITY TO ESTIMATE SAMPLING PROBABILITIES EXACTLY FOR DIFFERENT POINTS OF CONTROL. SUPPORTING DATA AND REFERENCES ARE INCLUDED. (DEP)