CURVE PERCEPTION AND ACCIDENTS ON CURVES: AN ILLUSIVE CURVE PHENOMENON?

THE DEFINITION OF A DECEPTIVE BEND IN A ROAD IS A BEND WHICH IS BY NATURE SHARPER OR MORE DANGEROUS THAN AS PERCEIVED BY THE APPROACHING DRIVER. THE ACCIDENT STATISTICS INDICATE THAT THE NUMBER OF ACCIDENTS ON A PARTICULAR BEND CANNOT BE ATTRIBUTED TO ITS GEOMETRICAL FORM. THREE TESTS WERE CARRIED OUT, IN WHICH FILMS AND PICTURES OF SECTIONS OF BENDS WERE USED TO TEST THE VARIABLES WHICH INFLUENCE THE PERCEPTION OF A BEND. THE RESULTS SHOW THAT THE PERCEIVED CURVATURE (CENTRAL CURVATURE AND TOTAL ANGLE) HAS NO BEARING. COMPARISONS BETWEEN BENDS HAVING HIGH AND LOW ACCIDENT FIGURES, WHICH WERE CHOSEN FOR THE EXPERIMENT BECAUSE OF THEIR GEOMETRICAL FORM, INDICATE THAT BENDS ON WHICH A HIGH NUMBER OF ACCIDENTS HAD OCCURRED WERE PERCEIVED AS BEING NEARER, WIDER AND MORE VISIBLE THAN BENDS WITH LOW ACCIDENT FIGURES AND NOT AS SHARPER AND MORE DANGEROUS. FURTHER ANALYSIS SHOWED THAT BENDS WITH A HIGH ACCIDENT FIGURE APPEARED TO HAVE A SIGNIFICANTLY SHARPER PERSPECTIVE ANGLE ON THE NEARSIDE FROM THE POINT OF VIEW OF THE DRIVER, WHICH WAS PARTLY DUE TO THE VERTICAL CURVATURE. UNFORTUNATELY DRIVERS APPEAR TO BE INDIFFERENT TO ALL THIS, PROBABLY DUE TO THE LEGAL LIABILITY IMPLICATIONS INVOLVED.