How does the mural decoration of the long tunnel sidewall affect the driver's speed control ability?

Abstract

Since a tunnel is dark and driving conditions are monotonous, drivers are prone to optical illusions, affecting driving safety in tunnels. Tunnel sidewall decorations can provide visual stimulation to prevent or reduce traffic crashes. Driving simulation experiments with a driving simulator and speed perception experiments with E-Prime software are performed to evaluate the influence of tunnel sidewall murals on the speed control of drivers in a long tunnel. Three mural designs (A2: 1.93 Hz, A3: 1.27 Hz, A4: 0.95 Hz) with different frequencies and a control group (no mural, A1) are evaluated. Four indicators of the driver’s speed control (speed, acceleration, stimulation of subjectively equal speed (SSES), and reaction time) are selected. The results show that the driver’s speed is significantly reduced in the middle of the tunnel and near the tunnel exit, and the driver's speed control is significantly enhanced by the murals. It is recommended to install murals in the middle and near the exit of the tunnel for optimal speed control. The SSES shows that tunnel murals affect drivers’ speed perception and alertness. As the frequency of the mural decreases, speed overestimation changes to underestimation, the degree of speed illusion increases, and the reaction time decreases. A difference is observed between the perceived and actual speed, and this difference depends on the mural’s frequency. Thus, choosing an appropriate mural frequency improves the mural’s effect. The results provide a basis for mural design on the sidewalls of long tunnels to improve tunnel safety, as well as a novel approach for speed reduction.