The Chinese-invested Phnom Penh-Sihanoukville Expressway in Cambodia opened to the public on Saturday for a month-long free trial to attract motorists driving on the first-ever expressway in the Southeast Asian nation.

Invested by the China Road and Bridge Corporation, the $2 billion expressway with a total length of 187 kilometers connects the capital Phnom Penh and the deep sea port province of Preah Sihanouk.

Cambodia's Ministry of Public Works and Transport (MPWT) Secretary of State Yit Bunna said the expressway project had been fully completed recently after more than three years of construction and put on a trial operation free of charge from October 1 to October 31.

"We urge all drivers to comply with the speed limits for your own safety and the safety of the others," he said at an event marking the inauguration of the highway for trial use. "We wish all passengers a safe travel on this expressway."

Sun Yaoguo, representative of the Phnom Penh-Sihanoukville Expressway project, said the freeway is the fruit of cooperation between China and Cambodia under the framework of the Belt and Road Initiative.

"The trial operation of this expressway shows that Cambodia has now entered the age of the expressway," he said. "We hope that all drivers will strictly abide by the rules and regulations set out by the MPWT to maintain order and safety."

According to the MPWT, the expressway can only be used by motorcycles that have a power of 500cc or more, and cars that can drive at a speed of 70 kilometers per hour (km/h) or more.

The minimum speed to use this toll road is 60 kilometers per hour and the maximum speed limit is 120 km/h for regular family cars, 100 km/h for heavy vehicles without trailers and motorcycles, and 80 km/h for trucks and cars with trailers.

With two lanes for traffic in each direction plus an emergency lane on each side and paved with asphalt concrete, vehicles will be able to reach their destination in about two hours on the expressway, instead of five hours on National Road 4.

Cambodian Ministry of Commerce's Undersecretary of State Penn Sovicheat said the expressway is crucial to helping boost economic growth, saving travel time and reducing logistics costs.

"It facilitates travel, enabling vehicles to drive faster and reducing congestion that we are having now," he was quoted as saying by Xinhua. "It will improve a lot for trade and tourists because the toll is not so expensive for using this route."

Chea Chandara, president of the Logistics and Supply Chain Business Association in Cambodia, said the expressway will inject a new impetus into the country's economic development as it links Phnom Penh and the Sihanoukville Autonomous Port.

"There's no doubt that the expressway will provide great benefit to our economic development as it will facilitate goods transportation between Phnom Penh and the Sihanoukville Autonomous Port, a major gateway for Cambodia's trade exchange with other countries," he was quoted as saying.

(With input from Xinhua)