Elected officials announced on Tuesday that the eighth and last of the main span towers on the $3.9 billion Tappan Zee Bridge project has been installed.

The officials, including Gov. Andrew Cuomo, spoke for the first time from the deck of the new span to celebrate the major milestone.

Cuomo also announced that the bridge is on budget and on track to open to traffic in just a few months.

Construction for the new Tappan Zee Bridge began in late 2013. Currently, 90 percent of the support structures to hold the 3.1-mile span are now in place connecting Rockland and Westchester counties.

"Today is a symbol of the incredible work that can be achieved when government truly performs for the people it is meant to serve,” said Rep. Nita Lowey.

Cuomo said the new bridge is expected to open to traffic in mid-2017, and will be completely finished in 2018.