FINAL REPORT ON THE MINNESOTA ROADSIDE STUDY

ACCIDENTS RELATED TO SPEED, TANGENT SECTIONS AND INTERSECTIONS WERE STUDIED. THE FOUR-LANE DIVIDED HIGHWAYS HAD THE LOWEST ACCIDENT RATE OF ALL ACCIDENTS STUDIED IN MINNESOTA AND ARE, THEREFORE, PRESUMED TO BE THE SAFEST. IT IS CONCLUDED THAT TRAFFIC VOLUMES INFLUENCE ACCIDENT RATES. CURVE SECTIONS AT THE ENDS OF LONG TANGENTS HAD HIGHER ACCIDENT RATES THAN WERE FOUND ON CURVES AT THE ENDS OF SHORT TANGENT SECTIONS. CURVES WITH RESTRICTIVE SIGHT DISTANCES PRODUCED AN AVERAGE ACCIDENT RATE TWICE THE RATE FOR TANGENT SECTIONS WITH RESTRICTIVE SIGHT DISTANCES. FOUR- WAY INTERSECTIONS HAD CONSISTENTLY HIGHER ACCIDENT RATES THAN THREE-WAY INTERSECTIONS WHEN TAKEN EITHER AS A GROUP OR BY COMPARABLE INTERSECTIONAL VOLUMES OR BY PERCENT OF CROSS TRAFFIC. WHEN ROAD SECTIONS WERE SEGREGATED BY TRAFFIC VOLUME GROUPS, A GOOD DEGREE OF CORRELATION WAS APPARENT BETWEEN THE NUMBER OF ACCESS POINTS PER MILE AND THE ACCIDENT RATE. HIGHWAY SECTIONS HAVING A HIGH FREQUENCY OF ADVERTISING SIGNS HAD HIGH ACCIDENT RATES. IT IS CONCLUDED THAT THE OCCURRENCE OF MOTOR VEHICLE ACCIDENTS CANNOT BE PREDICTED ON THE BASIS OF ROADWAY ELEMENTS AND ROADSIDE FEATURES. HOWEVER, IT IS EVIDENT THAT THESE VARIOUS ELEMENTS AND FEATURES, ALONE OR IN COMBINATION, MAKE VARYING DEGREES OF CONTRIBUTION TO ACCIDENT OCCURRENCE.