ATMS human factors experiments produce design guidelines

Public Roads, Spring, 1997 by Nazemeh Sobhi, Michael J. Kelly

Detailed studies of ATMS functions have found that automation may replace humans in many routine sensing, communication, data processing, and decision-making operations. For example, automated congestion detection and incident detection systems and automated response plans are part of many newer systems. The majority of ATMS functions, however, will still require actions, interventions, or supervision by humans. Automation will not eliminate the many problems that are often attributed to human operators, but it will probably change them into different forms.

Designing ATMS to Fit the Operator

We generally think of well-trained human operators as very flexible and able to adapt to new jobs, new workplaces, and new tools. As a result, operators' characteristics and requirements have rarely been examined in detail during ATMS design. Yet, the design of the ATMS concept of operations and the design of the operator-system interfaces - such as system controls and computer displays - can have a major impact on the efficiency of the operators. To help ensure that the operators perform their tasks effectively with a minimum of errors, their characteristics, capabilities, and limitations need to be carefully considered in the design of the system and in concepts and plans for its operation.

The military services have long recognized the importance of human factors issues in the design of complex systems. Airplanes, ships, control rooms, weapons, and personal items have all been made more serviceable through a standardized process that emphasizes the user or operator from the initial stages of the design process through the final test and evaluation. Human factors standards and design procedures for such systems and equipment are well-documented in numerous formal publications.

The concept of human factors design for ATMS is simple. The system needs to be designed and built to fit the operator. When tailoring a new suit, the tailor must know a great deal about the wearer - the sleeve length, the inseam, the neck size, the shoulder breadth, and many other dimensions. When designing a traffic management center, the engineer must know even more about the operator - eye height above the floor, color discrimination ability, ability to understand information on various displays, maximum (and minimum) workload, and scores of other measures.

Defining Human Factors Guidelines in the Laboratory

Under the sponsorship of the Federal Highway Administration, the Georgia Institute of Technology is conducting a series of experiments that will provide human factors design guidelines for future traffic management centers (TMC). The experiments are being conducted in a high-fidelity simulator of an advanced TMC. The simulator can duplicate the functions and operator workstations of real-world centers, including user-computer interfaces, automated support systems, and remote television cameras.

Based on a network of 13 computers, a large-screen projection television, and four 330-millimeter (13-inch) closed-circuit television (CCTV) monitors, the simulator can be configured into as many as four operator work consoles in one large room, with an experimenter's console in an adjacent observation room. Each operator workstation contains a Silicon Graphics monitor with a touchscreen, keyboard, and mouse. It also contains a monitor with a touchscreen that is configured as a communication control panel.

The projection television is in the front of the control room and typically displays a traffic situation map. The CCTV monitors can display realistic traffic scenes for any of 60 locations in the simulated roadway system. The simulator software includes a number of automated support systems that can be used by the operator to help detect and manage congestion and incidents.

Interfaces for Selecting and Controlling Remote Cameras

The first of a series of controlled laboratory experiments tested various control devices for selecting cameras and controlling their pan and zoom functions. The control devices included a joystick for camera control, a touchscreen on the system monitor, a mouse interface, and numerous keyboard interfaces. Results of the experiment led to rejection of the touchscreen and the joystick interfaces. Camera selection could be done by clicking on a camera icon on the map display with the mouse or by keying in a camera designation number on a keyboard. Pan, tilt, and zoom could effectively be controlled by using the keyboard cursor keys.

An additional finding was that the camera-control process was more efficient when the cameras had preset pointing angles rather than full manual control. With these cameras, a small number of pointing angles - toward areas most likely to have incidents - were selected for each camera. Pushing a button or key would move the camera through these selected views. The best interface provided the operator with both preset and manual control, allowing the use of preset controls to quickly survey the viewing area and manual control to fine tune the pointing angle for more detailed examination.