Optimization of tunnel entrance lighting under dynamic visual conditions based on perceived contrast threshold and recognition time analysis

Accurate determination of perceived contrast threshold <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi>C</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>min</mml:mo> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> is essential for optimizing the design and evaluation of tunnel entrance lighting. However, conventional methods often fail to adequately capture the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi>C</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>min</mml:mo> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> requirements under dynamic driving conditions. This study analyses the interactive effects of tunnel external luminance ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi>L</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">e</mml:mi> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> ) and tunnel entrance road surface luminance ( L b ) on drivers’ obstacle recognition ability. Under both positive and negative luminance contrast conditions, the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi>C</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>min</mml:mo> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> required to achieve reliable recognition (80% perception probability) and the associated recognition time ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi>T</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">r</mml:mi> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> ) were determined across various luminance combinations. The results indicate that compared to the result from the fixed value stimulation involving static visual targets, the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi>C</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>min</mml:mo> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> required for drivers to reliably recognize a fixed obstacle under simulated dynamic driving conditions increased by up to 35% ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi>L</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">e</mml:mi> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> = 4000 cd m −2 , <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi>L</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">b</mml:mi> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> = 75.8 cd m −2 ). The required <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi>L</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">b</mml:mi> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> rises in a nonlinear and accelerated manner as <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi>L</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">e</mml:mi> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> increases, to maintain the same visual recognition efficacy. Visual recognition performance under negative luminance contrast conditions is significantly better than under positive contrast, which is characterized by smaller <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi>C</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>min</mml:mo> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> and shorter <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi>T</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">r</mml:mi> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> . Luminance combination models for general safety and high safety recognition time are established. A comparison with existing standards revealed the limitations of current specifications for tunnel entrance luminance design.