"The extension of the Number 7 train from Times Square to 34th Street and Eleventth Avenue will create jobs now and result in countless long-term benefits when it's up and running," says Deputy Mayor Robert Lieber in a release. "And we're paying for it with the future revenues to be generated by the development at the Hudson Yards--a funding mechanism that essentially enables the new infrastructure to pay for itself."

Two TBMs, designed specifically for the hard rock conditions across the project line, will excavate two 7,100-foot-long tunnels running from the assembly chamber at Eleventh Avenue from 25th Street to 41st Street, and then east to link with the existing track at Times Square. The TBMs were tested last November by the manufacturer, German-based Herrenknecht AG, and then disassembled for delivery in three separate shipments by boat.

The first shipment arrived in early January, the second in early February and the third is scheduled to arrive later this month. Each machine will take about two months to assemble; the second one is scheduled for completion in mid-May.