Work to lift the 750-tonne deck sections into place began in September, with 36 out of 122 now installed.
Infrastructure Secretary Keith Brown visited the under-construction crossing over the Firth of Forth to view progress on the project, costing £1.35 billion to £1.4 billion.
It comes as the nearby Forth Road Bridge remains closed to all traffic due to ongoing repairs to a fault. It is hoped it will reopen by January 4.
Speaking about the construction of the new crossing, Mr Brown said: “Everywhere you look major milestones are being reached and significant progress being made.
“To name a few examples, concreting has been completed on the three towers, the south viaduct is complete with the concrete now being poured to complete the deck, final preparations are being made for the imminent launch of the north viaduct and great strides have been taken on the complex new and upgraded road networks to the south and north of the Forth.
“All of this is being achieved despite 2015 being remarkable in terms of adverse weather conditions occurring right throughout the year.”
He added: “The current closure of the Forth Road Bridge has brought into sharp focus the need for a new crossing over the Forth, the case for which was identified in Transport Scotland’s Forth Replacement Crossing study of 2006.
“Responding to that study, ministers announced our intention to build a new cable-stayed bridge by 2016.
“This challenging timescale was identified as necessary at the time due to the potential for future restrictions on the Forth Road Bridge.
“The project team are taking the chance to carry out works on and around the A90 near to the Forth Road Bridge when the closure is in place. This aims to minimise the impact and potential disruption to road users in future months.
“I am pleased to report the project remains on schedule and significantly under budget thanks to the Scottish Government’s diligent project management and the expertise and hard work of our contractors.”