The objective of this study was to identify means by which improved traffic control can improve traffic safety at work zones. The accident data base was derived from the coded information stored in the computerized data bank of the Ohio Department of Highway Safety. Coding errors and unreported accidents were recognized as limitations of the data base. Statistical analysis of statewide aggregate data failed to identify cause and effect relationships between accident characteristics and traffic control. The study was expanded to include the review of individual accident reports at nine construction sites. This approach proved very effective. The accident reports which always included a sketch and a description of the event often indicated that specific traffic control procedures and standards needed to be improved. It has become clear to the researchers that certain types of accidents at a given work zone can suggest specific problems with traffic control plans and/or with the implementation of the plans. Monitoring work zone accidents as they happen is of course the best way to recognize and eliminate problems.