Construction has begun on a new undersea high-speed railway tunnel project, one which will span an incredible 10 miles.
The Jintang Undersea Tunnel will connect China’s Ningbo City’s Beilun District to Zhoushan City as a critical component of the 48-mile Ningbo-Zhoushan Railway.
The project, which is being executed by China Railway’s 14th Bureau Group, is set to become the one of the world’s longest undersea high-speed railway tunnels, along with Japan’s Seikan Tunnel and the Channel Tunnel.
According to a report from CGTN, the Dinghai tunnel boring machine (TBM) – which weighs a staggering 4,350 tonnes and features 308 custom-designed cutters – began excavation at 42 metres below sea level near Zhoushan City in October, marking a major milestone for the project.
The tunnel’s construction officially started in May this year, with completion anticipated by 2028.
At its deepest, it will extend 78 metres below sea level and include a nearly seven-mile shielded section supporting train speeds of up to 250 kmh, or 155 mph.
The project faces challenges due to geological conditions, requiring modifications to the TBMs to manage 28 geological strata transitions.
Currently, Zhoushan and Ningbo are connected by a cross-sea bridge and ferries. The tunnel aims to reduce travel time to 30 minutes, down from the current one-and-a-half-hour journey.
The Jintang Undersea Tunnel passes under the Jintang Channel, a vital shipping route for Zhoushan Port, one of the world’s busiest by freight volume.
The Chinese tunnelling project involves navigating complex marine environments, crossing beneath oil pipelines, seawalls, docks, and shipping lanes.
The larger Ningo-Zhoushan High-Speed Railway project is being developed with a 27 billion yuan (£3.2 billion) investment.
It will connect the Zhoushan islands in Eastern China’s Zhejiang province with the mainland over a distance of 48 miles.
Construction on the Ningbo-Zhoushan high-speed railway project commenced in November 2022 and is also slated for completion in 2028.
The high-speed railway line will feature rail-road infrastructure. Supporting both high-speed trains and road vehicles, it includes a railroad bridge that will set a record as the longest combined railway-highway bridge in existence, according to Railway Technology.
Once operational, the railway is expected to strengthen the development of China’s Belt and Road Initiative and foster greater integration within the Yangtze River Delta region.
It is expected that the journey between Hangzhou and Zhoushan will take just 77 minutes, a journey which currently takes just under three hours by road.