Haptic information for reliable displays

In critical situations in the railway environment, people often have to rely only on what is displayed without being able to see the real-life situation. Is it possible to support what is generally only shown as visual... [ view full abstract ]

In critical situations in the railway environment, people often have to rely only on what is displayed without being able to see the real-life situation. Is it possible to support what is generally only shown as visual information by means of the other senses and thus increase safety? Today, audible information is very frequently in use. New technologies nowadays also offer haptic information. How well can visual information be combined with haptic information?
In automatic railway operations, a signaler does not need to rely on information that is displayed since the signaling and safety system in the background guarantees the necessary level of safety. If, however, an auxiliary operator action has to be executed and the signaling and safety system thus has to be deactivated by an operator in some areas, the user must be able to rely on the information actually displayed to him/her. Reliable displays are a solution for this purpose.
Siemens’ Mobility Management Business Unit develops reliable operator console systems for mass transit and mainline operations throughout the world. Today, desktop PC systems with several monitors are used as operator console systems almost exclusively. As part of a research project, Siemens is developing a new solution for an operator console with a reliable display on the basis of haptic and audible information on a touch screen platform. Instead of mouse clicking, the user now interacts with a touch screen which, from the point of view of human factors, involves a different type of interaction.
This paper intends to show how this solution of using haptic and audible information for a reliable display can function in the railway environment.
The haptic reliable display is based on a solution of diverse design which presents key safety-related process information to the user in up to three different ways. For instance safety-critical information, e.g. occupancy of a track section by a restriction, could be provided with haptic information in addition to visual information. If the user touches such a track section on the touch screen of a tablet PC, he/she is provided not only with visual information but also with a haptic stimulus matching the situation involved. If the visual and haptic information fails to match, e.g. the haptic information is missing, the user has to assume that there is a fault in the system and may no longer rely on what is displayed when making his/her decisions.
In two studies, we have investigated to what extent this process encounters acceptance by the user and whether there are differences in the combination of sensory stimuli.
The studies have shown that the idea to use a variation of feedback modes to reveal mistakes on a display works. Different combinations of haptic, acoustic, visual and combined haptic and acoustic feedback were researched.
While the studies have shown that potential users tend to prefer a haptic or combined haptic and acoustic signal over an acoustic signal alone, they were not able to ascertain any significant difference in the effectiveness of the various feedback modes.