Speed Recommendations During Traffic Light Approach: A Comparison of Different Display Concepts

Projects like INVENT or Travolution aim at optimizing traffic flow in cities by linking vehicles and infrastructure elements using infrastructure-to-car communication technologies. Traffic lights equipped with transmitters are able to inform the approaching vehicles about the current and future state of the traffic light control. This information can be used to optimize the speed profile while approaching an intersection. As current vehicles will not perform any speed changes autonomously, an intuitive and easy-to-read human machine interface is needed to present the speed recommendations to the driver. Three different ways of in-vehicle information presentation were evaluated with 27 participants in a static driving simulator. The first variant is a simple countdown which presents the remaining seconds of the red or the green phase, respectively. The second variant shows the minimum or maximum speed recommendation in a textual manner. The third alternative uses a red and green area on the speed indicator scale. All three approaches were tested regarding their comprehensibility, acceptance, effectiveness and distraction. The results indicate that the non-textual speed indicator display is preferred by most of the individuals and also has advantages concerning minimization of acceleration and deceleration actions. 1 Author for correspondence: Stephan Thoma, BMW Group Research and Technology, Hanauer Str. 46, 80992 München, Phone: +49 89 382 30628, e-mail: [email protected] 2 http://www.invent-online.de 3 http://www.vt.bv.tum.de/uploads/rbraun/Travolution_Plakat_2007-07-09_TUM-VT.pdf