The 21-foot diameter machine, named Balto, came into view at the site of the future LRT station at Broadway and John Street at roughly 2:30 p.m. local (Pacific) time.

The first tunnel, bored through by "Togo," reached Capitol Hill on March 21. A third machine, called Brenda, is digging the second of two one-mile tunnels between Capitol Hill and Westlake.

The three tunneling machines are key construction elements for the $1.9 billion, 3.1-mile U-Link extension of the LRT system from Westlake Center to the station at Cal Anderson Park and the University of Washington campus.