The presented research used a driving simulator to study the effect of isolated vertical crest curves overlapped with horizontal curves on driver's perception and behavior. The curves were consistent with the existing design standards. The research was conducted in four phases: (1) Design a test road with road design software; (2) Convert the designed road to a scenario in the driving simulator; (3) Execute simulation experiments with 48 subjects; and (4) Analyze statistically the obtained simulation results. The participated in the experiments subjects were surveyed to assess their perception of the curve sharpness and the available sight distances. The survey results indicate that the driver's perception of curves depends on the algebraic difference of grades. On the other hand, the operating speeds on different curves were not statistically different from each other. In the matter of fact, the difference between the lowest and highest operating speeds on curves was only 10 km/h. Surprisingly, the operating speeds on a flat curve tended to be lower than on the curves superimposed on vertical crest curves. The likely causes of these results are discussed in the paper.     «

The presented research used a driving simulator to study the effect of isolated vertical crest curves overlapped with horizontal curves on driver's perception and behavior. The curves were consistent with the existing design standards. The research was conducted in four phases: (1) Design a test road with road design software; (2) Convert the designed road to a scenario in the driving simulator; (3) Execute simulation experiments with 48 subjects; and (4) Analyze statistically the obtained si...     »