A LABORATORY STUDY AND COMPLEMENTARY FIELD STUDY WERE CONDUCTED TO EVALUATE THREE ALTERNATIVE FORMS OF ADVANCE DIRECTION SIGNS FOR USE AT INTERSECTIONS OF COMPLEX LAYOUT, ROUNDABOUTS AND SUCCESSIVE ROAD JUNCTIONS IN CLOSE PROXIMITY. THE SIGN FORMS INVESTIGATED WERE DIAGRAMMATIC, STACK AND A MODIFIED STACK FORM IN WHICH THE ARROWS CONTAINED MORE DIRECTIONAL INFORMATION THAN THOSE ON CONVENTIONAL STACK SIGNS. THERE WAS NO SIGNIFICANT OVERALL DIFFERENCE BETWEEN SIGN FORMS IN THE LABORATORY EXPERIMENT IN TERMS OF ACCURACY OF ROUTE SELECTION WHEN THERE WAS INFORMATION AVAILABLE FROM INTERSECTION DIRECTION SIGNS AND FROM THE INTERSECTION ITSELF AS WELL AS FROM THE ADVANCE DIRECTION SIGN. AT COMPLEX INTERSECTIONS WHEN ONLY THE ADVANCE DIRECTION SIGN WAS VISIBLE, PEOPLE MADE SIGNIFICANTLY MORE ERRORS WITH MODIFIED STACK THAN WITH DIAGRAMMATIC SIGNS; STACK SIGNS HAD INSUFFICIENT DIRECTIONAL INFORMATION TO BE INCLUDED IN THIS COMPARISON. INDIRECT PERFORMANCE MEASURES (SECONDARY TRACKING TASK PERFORMANCE) INDICATED THAT DIAGRAMMATIC SIGNS WERE MORE DEMANDING OF PERCEPTUAL AND PROCESSING CAPACITY THAN WERE STACK AND MODIFIED STACK SIGNS. RESULTS OF THE FIELD EXPERIMENT WERE CONSISTENT WITH THE ABOVE FINDINGS. THERE WAS A TENDENCY FOR VEHICLE LAND PLACEMENT TO BE BETTER WITH A DIAGRAMMATIC SIGN THAN WITH A STACK SIGN; HOWEVER, THIS DIFFERENCE WAS NOT STATISTICALLY SIGNIFICANT (A). THE NUMBER OF THE COVERING ABSTRACT OF THE CONFERENCE IS IRRD NO 255423.
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