As China's overall national strength enhances and the Chinese economy grows, the country's highway network also expands from plain regions to mountainous areas and from urban areas to more distant rural regions. Also growing at a fast pace is the total length of the country's highway tunnels. With more and more highway tunnels being built, the number of long-length and complicated tunnels along with related cases of tunnel safety accidents is also on the rise, making the safe operation and management of hig...