Effectiveness of Diagrammatic Guide Signs at Complex Interchanges

Abstract

The present work investigated if drivers’ interpretation of diagrammatic arrow signs dropped in accuracy as the number of lanes at an interchange increased. A set of diagrammatic arrow signs were shown to 183 participants as part of a slideshow. Participants were prompted with a navigation objective, briefly shown a picture of a diagrammatic arrow sign that communicated the necessary information for navigation, then they were asked to make a navigation decision. The three factors considered were 1) the total number of lanes on the roadway, 2) the parity of lanes included in each of two branches on the sign, and 3) the difficulty of the navigation task decision. When positioned in an edge lane (easy condition), drivers were good at determining where their lane would lead. When positioned in a center lane (hard condition), their navigation performance improved with an odd number of lanes.