Research on Billboard Setting Parameters for Long Steep Slope Sections of Freeways Based on Driving Simulation Experiments

Billboards are commonly erected along freeways in the western mountainous regions of China. The placement of billboards on long steep slopes not only increases the driving load but also distracts attention, affecting driving safety. Driving simulation experiments were conducted on 20 groups of different billboards setting parameters and longitudinal slope gradients. Lateral displacement and speed zone area indicators were constructed to analyze the significance of their impact on driving behavior. The speed zone area was selected for paired sample T-tests to determine the start and end points of significant behavioral changes in 16 control experiments. Results show that the billboard support style, distance from the road edge, slope gradient, and slope length all have a significant impact on the start and end points of driving behavior. It is not suitable to set up billboards on slopes with a gradient exceeding 4%, even for wall-style billboards with the least impact.