A 161.9-kilometer stretch of road from Jinan to Weifang in Shandong province became China's first zero-carbon expressway in September last year.

From the air, the expressway resembles a winding dragon whose scales are made of photovoltaic panels. This project has used the road's verges, service areas, toll stations and building rooftops to form an integrated solar power generation installation.

The panels on the verges on both sides of the expressway stabilize the soil as well as generate electricity. In addition, the panels installed on isolated spots along the road utilize otherwise idle land, providing a stable power supply for the expressway, said Xie Guomu, director of the Jinan-Weifang expressway project office of Shandong Hi-Speed Group.

"Achieving 'zero carbon' involves long-term and comprehensive planning. Through emission reduction measures, the total carbon emissions during the expressway's operational period are equal to or less than the total carbon reductions, achieving 'zero emissions'," Xie said.

The photovoltaic facilities and smart systems have significantly contributed to the expressway's carbon reduction efforts.

The photovoltaic power installations along Jiwei Expressway have a capacity of 68 megawatts. Over a 25-year operational period, the total electricity generated is expected to reach approximately 1.7 billion kilowatt-hours, with a total carbon reduction of about 1.52 million metric tons, Xie said.

The photovoltaic panels installed above tunnel entrances provide electricity directly to the tunnel's equipment. Among the equipment used in the tunnels is an adaptive lighting system that automatically adjusts brightness based on external light conditions and vehicle speed. This system ensures safe driving while reducing energy consumption.

Lu Youfu, business manager of the energy and environment department of Shandong Hi-Speed Group, said, "The company has also launched a smart road network management system and promoted the use of electronic toll collection, which has greatly improved traffic efficiency and is expected to reduce vehicle carbon emissions by 140,000 tons annually."

The expressway also uses a radar and video roadside sensing system to detect traffic events, with a key event detection accuracy rate of over 97 percent. By utilizing comprehensive monitoring, reliable emergency response, and real-time forecasting and warning technologies, the expressway ensures precise vehicle dispatching and guidance, enhancing driving safety and traffic flow.

In response to winter snow conditions, the expressway employs technologies to improve driving conditions on critical sections such as major bridges, continuous slopes, shaded areas and tunnel entrances and exits.

Service areas are another major area where carbon emissions can be reduced due to their relatively concentrated nature, said Lu.

At the Jinandong service area, which covers 20 hectares, photovoltaic panels have been installed on roofs and carports, creating a photovoltaic power station with a total installed capacity of 3.2 megawatts, complemented by energy storage equipment.

The photovoltaic system at the service area generates over 10,000 kilowatt-hours of electricity daily, equivalent to saving 1,200 tons of standard coal annually.

"The green electricity ensures the power needed for new-energy vehicles running on the expressway," said Lu.

In the first half of this year, the daily average traffic flow on expressways nationwide was 35 million vehicles, with new energy vehicles accounting for 4.7 million, according to the Ministry of Transport.

As new-energy vehicles on the road increase, the demand for electricity means that service areas will need to accelerate going green.

By the end of last year, 17 provinces had started building zero-carbon service areas along their expressways.

Shandong Hi-Speed Group aims to construct more than three additional zero-carbon expressways and over seven zero-carbon service areas by the end of 2025, it said.

zhaoruixue@chinadaily.com.cn