HONG KONG -- Cross-border buses operated by Hong Kong companies on Friday started trial runs on the Hong Kong-Zhuhai-Macao Bridge (HZMB) in preparation for the bridge's upcoming opening.

The trial runs, jointly arranged by the governments of the Chinese mainland, the Hong Kong Special Administrative Region (SAR) and the Macao SAR, would last for three days and aimed at testing the readiness of boundary crossing facilities of the three places, the Hong Kong SAR government's Transport and Housing Bureau told Xinhua.

Two major cross-boundary coach trade associations in Hong Kong were invited to send buses and members to participate in the trial runs.

Freeman Cheung, secretary of Hong Kong Guangdong Boundary Crossing Bus Association, said his association would run one bus with about 10 passengers on Friday and Saturday respectively as part of the trial runs.

"Our bus started at noon from the Hong Kong Boundary Crossing Facilities and ran all the way to Zhuhai in about 40 minutes," he said, adding that "the journey was smooth."

Alan Chan, secretary of another trade association who participated in the trial runs as a passenger, said the clearance procedures at boundary crossing facilities of the three places all went on well and smoothly.

"The boundary crossing facilities of Zhuhai and Macao, in particular, are operated in a collaborative way, which helps remarkably shorten the time needed for the clearance procedures," he said.

The HZMB, situated at the waters of Lingdingyang of Pearl River Estuary, is a mega-size sea crossing linking the Hong Kong SAR, Zhuhai city of Guangdong Province and the Macao SAR.

The 55-km bridge is the longest bridge-and-tunnel sea crossing in the world.

The bridge is meant to meet the demand of passenger and freight land transport among Hong Kong, the Chinese mainland and Macao, and to establish a new land transport link between the east and west banks of the Pearl River.