Despite China having built one of the world's largest road networks, congestion hot spots are an inevitability, so researchers are working on a shift from building roads to managing them better.

At the Tongzhou laboratory, researchers are testing out these intelligent transport systems to make them reliable enough for real-world use.

In a 250-meter tunnel, rain can be made to fall at the push of a button, while fog, low visibility and water-covered road surfaces can be repeatedly recreated.

Li Zhenhua, a senior engineer at the laboratory, said the facility allows researchers to bring dangerous weather conditions indoors, instead of waiting for them to appear on real roads.

"Extreme weather on real roads is difficult to predict and even more difficult to test safely," Li said. "Here, we can reproduce the same scenario again and again, compare the data and improve the system step by step."

An eight-degree-of-freedom traffic safety simulator with a 360-degree panoramic projection system, surround sound and a motion platform, is used to recreate different vehicle types, roads and weather conditions, including rain, snow, fog and wind. This system allows the researchers to test driving behavior and intelligent transport technologies without exposing vehicles or people to real danger.

The lab also has an automated driving test track covering road scenarios including expressways, urban roads, national and provincial highways, and rural roads. It includes intersections, ramps, toll stations, bus stops and a simulated tunnel, supporting the research, evaluation and demonstration of automated driving technologies.