The elusive and increasingly expensive extension of the Second Avenue Subway is taking a key step forward.

This week, Governor Kathy Hochul announced that the MTA has starting soliciting the first construction contract for the phase two extension of the subway, which will run to 125th Street in Harlem.

125th Street, platform viewMTA

"As part of my administration's efforts to advance transit equity across New York State, the Second Avenue Subway project will expand critical public transportation service to East Harlem, creating more opportunity for residents," said Hochul in a press release. "We remain committed to keeping this long-envisioned project moving along swiftly for East Harlem, and I am proud to see it moving one step closer to reality."

Phase two of the Second Avenue Subway will run approximately 1.5 miles, extending service from 96th Street to 125th Street, and then west on 125th to Park Avenue. Plans call for new stations at 105th Street and 116th Street on Second Avenue, and then a new passenger connection at the existing 125th Street Station on the Lexington Avenue line. An entrance off of Park Avenue will also allow transfers to Metro-North's 125th Street Station.

Each new stop will include standalone buildings for mechanical functions, and potentially commercial and community spaces. The full project is expected to serve an additional 100,000 daily passengers.

Construction is set to begin later this year.

106th Street Station entranceMTA

The first phase of the Second Avenue Subway, criticized for its more than $4.6-billion cost, added 1.8 miles of track and three new stations when it opened in early 2017. However, phase two is coming in with an even more eye-popping price tag: an estimated $6.95 billion.

Despite the increased cost, which to some degree reflects increased costs for construction projects nationwide, the MTA has indicated that it has learned lessons from the initial phase of the project which could save time and money.