TRAFFIC CONTROL DEVICES. IN: HUMAN FACTORS IN TRAFFIC SAFETY

Traffic control devices (TCD) are meant to provide information to regulate, warn and guide road users. Provided is a brief examination of relevant research that indicates that TCDs, especially signs, can easily be missed or misunderstood by drivers. Often the intended message can confuse or mislead drivers because of information overload, use of unknown symbols, ambiguous word messages, print that is too small, etc. Also, even well designed TCDs are frequently placed in environments that make them difficult to detect. Not only do signs, the most prevalent device on the road, appear to present the most difficulty for drivers, but signals and markings are often misunderstood as well. Older drivers, in general, have more difficulty than others in detecting and understanding TCDs. It is difficult to determine the extent to which poor TCDs contribute to traffic accidents, as failure for drivers to comply with TCDs may be due to failure to notice them, lack of understanding, inadequate legibility distance, etc.