The focus of this study was on navigational signage that is intended to assist motorists to anticipate the correct roundabout exit and to select an appropriate approach lane for that exit. The objective was to support recommendations on double-lane roundabout signage to the Federal Highway Administration's Manual on Uniform Traffic Control Devices Team and to the National Committee on Uniform Traffic Control Devices (NCUTCD). The Traffic Control Devices Pooled Fund Study identified the need for this research. Four currently used navigation-signing methods (Conventional, Maryland, Diagrammatic, and New York) were evaluated. In the study, volunteer participants were shown guide signs and markings in a roundabout context and asked to identify which lane they should be in and which exit they should use for a given destination. Response correctness, speed, and confidence for lane choices and leg identifications were assessed. Overall, the conventional and diagrammatic signs yielded the best performance, particularly with respect to participants' reaction time and decision confidence. The current NCUTCD markings subcommittee recommendations for lane control markings were used in the contextual stimuli presented to participants. For all navigation sign types, lane selection performance was below 70 percent correct, and not far from chance given the assumption that in the absence of other information drivers would use the left lane for left turns, the right lane for right turns, and either lane to continue straight through. Further research is recommended to determine whether the current recommended markings are sufficient for driver comprehension.
Abstract