DURING THE COURSE OF AN ACCIDENT INVESTIGATION, THE OFFICER MUST BE ALERT TO DEFECTS IN THE TRAFFICWAY SO THAT HIGHWAY ENGINEERS CAN CORRECT ANY DESIGN DEFICIENCIES. CONDITIONS DISCUSSED AS CONTRIBUTING TO TRAFFIC ACCIDENTS ARE VIEW OBSTRUCTIONS, REDUCED VISIBILITY, SURFACE CONDITIONS, ROAD ALIGNMENT, AND THE FAILURE OF TRAFFIC CONTROL DEVICES. STEPS IN DETERMINING IF ANY OF THESE FACTORS WERE INVOLVED IN AN ACCIDENT ARE DESCRIBED. OFTEN, THE ONLY IRREFUTABLE MEANS FOR DETERMINING HOW AND WHY AN ACCIDENT OCCURRED IS BY EXAMINATION OF THE PHYSICAL EVIDENCE AT THE SCENE. THE SEVEN BASIC CLASSES OF ROADWAY EVIDENCE DISCUSSED ARE DEBRIS, MARKS ON THE ROADWAY BY HARD OBJECTS, TIRE IMPRINTS, TIRE SKIDMARKS, DAMAGE TO ROADSIDE OBJECTS, AND MISCELLANEOUS ROAD MARKS. THE INVESTIGATION OF EACH OF THESE CLASSES OF EVIDENCE IS DESCRIBED. A TEST COVERING THE MATERIAL PRESENTED IS INCLUDED. (RCB)