The US$76m (£62m) Herrenknecht machine will have a 16.5m diameter, making it one of the largest TBMs in the world. It will dig an 8km tunnel that will extend the heavy rail service from Berryessa/North San Jose through Downtown San Jose into Santa Clara.

The TBM will be designed to operate in areas with higher water tables and the geology of sands, gravel, silts, and clays in the South Bay. It will progress around 9-12m a day and take three to four years to dig the tunnel.

The completed tunnel will have an inner diameter of 14.6m and house twin tracks and three station platforms. It is the first rail project in the US to be constructed by a single bore.

VTA will launch a TBM naming contest before the machine arrives in the US.

Last year Kiewit Shea Traylor joint venture (KSTJV) was awarded the design-build contract for the tunnel and trackwork.