However, even with powerful computers, much of the communication and most of the critical decisionmaking are done by human operators. Humans talk on telephones and radios; humans operate cameras that provide views of the roadway; humans monitor computers' actions and correct mistakes; and humans turn computers on and off.
Designing the center to optimize the performance of both computers and human operators is an important job for the designer. The center design must take into account the characteristics, capabilities, and limitations of people, communication systems, and computers in order to promote quality traffic management.
One of the best sources of information on which to base design recommendations is past experiences with similar designs. The purpose of this study was to identify and document human-related lessons learned in the design and operation of similar operation control systems.
The study raised a series of human factors design issues: (1) a design process centered on user needs, (2) automation, (3) staffing, (4) management, (5) design of the interface between users and equipment, and (6) ergonomic and environmental considerations. The interviews revealed that during center design, little attention is typically paid to specific issues that could enhance operator performance. While a few of the centers visited used human factors consultants or universities to provide design guidance, only one adopted a user-centered design process that would have been recommended by human factors engineers.
The centers that were visited varied widely in their approaches to automation. One European system (figure 1) approached full automation of its responses to congestion. A Canadian center used automated responses to routine and incident-related congestion, but manual incident location and reporting to emergency agencies. Centers in the United States (figures 2 and 3) tended to be more labor-intensive in their procedures. Automated systems have the potential of improving the speed and precision of TMC actions; however, most are still too unreliable to be widely accepted and used by the operators.
All but the most highly automated centers depended heavily on the use of remote television cameras to identify congestion and traffic problems. Some centers provided the operators with large walls covered with dozens of television monitors, while other centers used relatively few.
There are important questions about how television can best be applied to support the operators and how the remote cameras can best be controlled. Centers also differ on the qualifications required of their operators. Some centers require only a high school diploma. Others hire college students for part-time employment. Still others require a college engineering degree. One center was staffed entirely by police officers, while several had police liaisons on their staff.
The design issues identified during the study will be addressed in a handbook of human factors guidelines and recommendations for ATMS design that is scheduled for 1995.