Traffic systems are undergoing important changes with the advent of intelligent transport systems (ITSs). Safety remains the predominant preoccupation when integrating an ITS into vehicles. Intelligent technologies may potentially improve traffic safety. They may also affect it adversely. Interactions between humans and ITSs (human-machine interaction) should therefore be carefully evaluated. The effect on safety depends on specific advanced technologies and the manner in which these are incorporated into the vehicle. ITSs should be developed as user-centered solutions rather than technology-centered answers (Noy, 1997). Greater efforts must be directed toward understanding and accommodating the human element in road transportation so that future transportation objectives may be achieved (e.g., reducing vehicle crashes). According to Noy, there is a need to expand the scope of traditional human factors on understanding human interactions with the elements of the system. There is also increasing recognition of the urgent need for systematic procedures and criteria for testing the safety of ITSs prior to large-scale market penetration.
Vehicles are now equipped with a number of warning and safety devices to prevent injury-causing accidents (Nanthavanij, Yenradee, & Techapichetvanich, 1995). Standard safety devices can be divided into two groups: passive systems, which act without any human interaction (e.g., airbags), and active systems, which are supposed to be dependent on human action and/or regulation (e.g., noncontact obstacle sensors). The use of a new intelligent safety feature not only provides an effective warning approach but also helps to control critical situations. For example, braking and steering are required when avoiding an obstacle. The antilock braking system keeps the vehicle under the driver's control as the wheels go on turning, even in the event of extreme braking. However, it has been shown that in order for this safety device to be effective, drivers should know how it works (Priez, Petit, Tarriere, Dittmar, & Vernet-Maury, 1992). As action (braking and steering) is associated with the functioning of the safety system, drivers should adapt their activation (physiological arousal) and their vigilance (focusing attention) to the surrounding context--a critical situation involving collision avoidance. With or without safety systems, crashes will be difficult to avoid if drivers' behavior is not carefully adapted.
Of the various roles for ITSs, that of an assistance system during bus docking should be evaluated. Parking aids that are becoming available or are soon to come on the market should be placed in the category of safety systems involving human-machine interaction. They use cameras or infrared techniques and are especially helpful to persons with mobility problems (e.g., to enable them to get onto the bus easily). Such assistance involves several means for longitudinal and lateral control of the bus. Reduced workload is thought to result from using such navigation systems, helping the driver to maneuver by assisting him or her in monitoring the proper functioning of the system (Farber, 2000). However, the true impact of the system on drivers must be studied by demonstrating the particular importance of the specific layout of the human-machine interface, in order to guarantee high acceptance and minimal distraction from traffic.
A tight-maneuver precision dock system positions a bus or commercial vehicle precisely in relation to the curb or loading board. The driver maneuvers the vehicle into the loading or boarding area and then shifts to automation. Sensors continuously determine the lateral distance in relation to the end of the vehicle loading/boarding area. The driver can override the system at any time by braking or steering and is expected to monitor the situation and take emergency action if necessary (e.g., if a pedestrian steps in front of the vehicle). When the vehicle is properly docked, it stops and reverts to manual control. In freight or bus terminals, this service could increase facility throughput as well as safety. Because the system must be monitored, the aim of this paper is to investigate the role of a tight-maneuver precision dock system on bus drivers' mental load.
Assessing mental workload is central to motor vehicle driving studies, whether one is elaborating a cognitive model of the task, creating high-performance tools, or evaluating human-machine interactions. However, despite its ubiquity, workload is hard to pinpoint. It is …