Driver’s visual luminance model considering the reflection characteristics of a tunnel’s inner wall: Theory and practice II

In the first part of this study, we had established a visual luminance model for a tunnel considering the driver and verified the accuracy of the model using a 1:10 scale simulation tunnel model. Although the established visual luminance model is based on a straight-wall side wall and cement concrete pavement, most of the design of the practical tunnel is based on the curved-wall side wall and asphalt concrete pavement. The core of this study concerns this distinction. For example, what is the accuracy of the model in the practical tunnel? Can it simulate the reflection characteristics of the material in an actual tunnel? Can it solve the application problems in general practical engineering? In view of these issues, in this study, we derive a formula for a three-dimensional coordinate transformation based on a tunnel’s geometric section structure and apply it to the established visual luminance model to solve a calculation problem of the model for a curved-wall side wall. In addition, the model describing the bidirectional reflectance distribution function is optimised and a more accurate six-parameter model is used to express it, verifying the reliability of the optimisation model. We design a standard field test plan, collect data, and analyse the calculated model results based on the test data. The results show that the relative error rate between the theoretical results and measured data can be controlled within 5.7%, confirming the accuracy of the model.