2nd Avenue subway celebrates milestone Thursday

September 22, 2011 4:46:48 AM PDT
The Second Avenue subway marks an important milestone Thursday.

The MTA says it will finish tunneling for the subway's first phase.

A giant tunnel-boring machine is scheduled to break through a wall of rock under 63rd Street into an existing tunnel.

Over 16 months, the machine has dug two tunnels, 29 blocks long.

The average speed was about 50 feet per day.

Actual trains aren't expected to start running until the end of 2016.