The 5km-long route goes for 50m beneath the sea, providing access to Lantau Island and Hong Kong international airport. AECOM and Dragages Hong Kong are active on the project, with Herrenknecht constructing the giant TBM.

Also involved are Bouygues Travaux Publics, which has fitted the 17.6m wide TBM with a trio of innovations developed by their research and development team.

Firstly, they have installed a group of sensors and instrumentation into the TBM heads called ‘Mobydic’, which maps the cutting face and wheels to check for wear and to assess how much progress the gargantuan machine makes.

Secondly, the ‘Snake’ is a suitably serpentine sobriquet for the remote controlled arm unit that works to unclog and clean the cutter heads to allow for easier inspection.

Thirdly – and lastly – ‘Telemach’ is being used for the first time. This is a robot that can be sent forward to change peripheral cutting wheels mechanically.

Overall, the site offers engineering challenges, not least the fact that pressure down there is more than 5 bar. Furthermore, specialist divers carry out maintenance operations as required.

Construction of the northern connection is scheduled for completion during 2018, but the southern end’s finishing date is still under review.