Domestic 14-Metre Giant Shield Tunnelling Machine “Pioneer” Rolls Off Production Line for Taihu Underwater Rail Tunnel

A domestically built 14-metre-class ultra-large-diameter shield tunnelling machine named Pioneer was formally rolled out in Changsha, Hunan Province, on 17 July. Developed collaboratively by China Railway 14th Bureau under China Railway Construction and CRCC Heavy Industry, the machine will be deployed on the Taihu crossing tunnel section of the Wuxi–Yixing Intercity Railway, known as the S2 Line, the first ultra-large-diameter shield tunnel running beneath Taihu Lake in China.

The S2 Line links Wuxi and Yixing in Jiangsu Province and serves as a vital infrastructure project to build a half-hour commuter corridor between the two locations and advance integrated development across the Yangtze River Delta. 

Stretching roughly 61.48 kilometres with a design operating speed of 160 kilometres per hour, the route includes nine stations and crosses Taihu Lake twice. The 21.6-kilometre single-tube double-track tunnel beneath Taihu Lake forms the critical control section of the whole scheme.

The Pioneer machine boasts an excavation diameter of 14.02 metres, a total length of approximately 112 metres and an overall weight of 3,200 tonnes. It will undertake tunnelling work across two separate sections of the sub-lacustrine tunnel. 

Fitted with a pressurised composite cutterhead, the equipment carries a full range of disc cutters, drag bits, overcutting tools and gauge cutters that can be reconfigured to suit varying geological conditions along the alignment.

The tunnelling system integrates multiple advanced technologies, including high-precision navigation, intelligent excavation management, automatic measurement of shield tail clearance and segment floating monitoring systems. 

It also incorporates a high-power rock crusher and a synchronous grouting system using thick single-component mortar to establish a multi-layer safety framework for steady, efficient excavation.

Once fully completed, the S2 Line will connect major transport hubs including Shuofang Airport, Wuxi Railway Station and Yixing High-speed Railway Station. Interchanges will be available with Wuxi Metro Line 1 and the Wuxi–Jiangyin S1 Line, forming an interconnected rail network serving integrated mobility across Wuxi, Jiangyin and Yixing.

Construction teams will transport the shield machine to the project site and prepare assembly and launch arrangements. Ongoing technical optimisation will support safe tunnelling beneath the lake amid complex subaqueous geological conditions.