Fig. 2
![Fig. 2](http://media.springernature.com/full/springer-static/image/art%3A10.1186%2Fs40064-016-2261-y/MediaObjects/40064_2016_2261_Fig2_HTML.jpg)
Specific environment design in Zhongnanshan Tunnel of G65 Baotou–Maoming Expressway, China. a Connection section of short tunnel; b lighting section inside long tunnel
Specific environment design in Zhongnanshan Tunnel of G65 Baotou–Maoming Expressway, China. a Connection section of short tunnel; b lighting section inside long tunnel