Investigating the Impacts of Graphical Route Information Panel Layouts on Drivers’ Comprehension and Response Time

Abstract

Graphical route information panels (GRIPs) are an alternative to conventional text-based variable message signs to address different traveler information needs. Since drivers are traveling at higher speeds on the motorways, they have to quickly comprehend and correctly respond to the graphical information displayed on a GRIP. Design elements like the shape of the route map, the meaning of colors indicating congestion and the font sizes of main and minor destinations along the route can influence the comprehension times of drivers. In this study, GRIPs with two purposes (congestion information and event destination information) were presented to 49 Belgian drivers in a computer-based task. All GRIPs were presented on an abstract and naturalistic motorway network shape. Half of the GRIPs were presented with congestion-related colors (red-only or red–orange), and the other half were presented with additional destinations being displayed in different or same font sizes to facilitate drivers visual search on the GRIP. Firstly, travel information statements were presented to the participant, followed by a displayed GRIP layout. Afterward, the participant had to indicate as fast as possible whether the subsequently shown GRIP confirmed the same travel statement. The subjects’ response accuracy and response times were recorded to assess drivers’ quick comprehension of the graphical content. The results of a repeated-measures ANOVA revealed that for GRIP displaying congestion, the red-color element (and not the map shape) significantly reduced drivers response times. A survey among participants also revealed a preference for two-color congestion information, if shown on an abstract map shape. An abstract map shape in combination with different font sizes for major and minor destinations improved drivers’ comprehension and response times to the GRIP, whereas different destination font sizes displayed on a naturalistic map had the contrary effect. The results highlight the importance of graphical design elements with respect to the information purpose.