South China’s Hainan Province, now a popular destination for middle-class Chinese to spend their winter vacations, is expected to be connected with South China’s Guangdong Province, via a first-of-a-kind tunnel set to rake in more than 150 billion yuan ($21.84 billion) in investment, media reported on Thursday.

The road-rail tunnel will run across the Qiongzhou Strait at a length of about 80 kilometers and will help tackle transport dilemmas in Hainan, where China set up a free trade port in April, according to a report by China Ocean News.

Tourists usually travel to the island province via boat or air, which has resulted in travel issues in the past. For example, during the Spring Festival this year, ferry and air services were shut down due to bad weather conditions, causing week-long traffic jams and delays on the disaster-prone island.

This project has been submitted for approval by the National Development and Reform Commission, the country’s economic planner, the report said. However, construction work will face huge challenges from a technical perspective.

Local authorities have been studying the feasibility of the tunnel project for two decades, with the aim of tackling the island’s transport dilemma and boosting local economic growth, according to China Ocean News.