The Transmission Gully motorway north of Wellington was due to open in late 2020.

Motorists won't be driving it for at least another year but they can now catch a birds-eye view of Transmission Gully.

The New Zealand Transport Agency have released new aerial photographs and videos of the $850 million project, mostly hidden from public view.

The footage includes the 226 metre long, 60m high Cannons Creek bridge which has now had its concrete deck poured.

NZTA Watch the final concrete pour take place on Transmission Gully's 230m long bridge.

Construction was now 80 per cent complete, the agency said.

READ MORE:

* New photos show progress of Transmission Gully one year out

* Transmission Gully completion date extended, more delays likely

* No toll for Transmission Gully, NZ Transport Agency announces

Construction began on the 27 kilometre-long motorway in April 2015 which, once completed, will connect Linden in north Wellington to Paekākāriki on the Kāpiti Coast.

Supplied Fourteen kilometres of the new motorway is now at pre-pavement level.

Initially meant to open in April 2020, the project was revealed last month to be "considerably behind" schedule, with the NZ Transport Agency now expecting a November 2020 opening date.

The agency blamed weather and seismic events, including the need for resources to be diverted following the 2016 Kaikoura earthquake.

In August, after years of speculation, the agency announced the motorway would not be tolled.

Supplied The Cannons Creek Bridge is the biggest of the project.

With 7.6 million hours worked by the construction team since the project began, the agency's most recent update said 89 per cent of the project's structures were now complete.

There are still 650,000 cubic metres of earth left to move.

The Willowbank Quarry, off State Highway 58 (SH58) to the west of Judgeford, will provide a specific 40 millimetre sized rock for the project.

SUPPLIED Eighty per cent of the project's construction is now complete.

About 400,000 tonnes will be extracted from the quarry and once processed, it will be trucked to the surrounding project areas for use in road pavement construction.

Transmission Gully project by the numbers

650,000 cubic metres of earth left to move

89 per cent of the project's structures are complete

14 kilometres of the new motorway is at pre-pavement level

61 per cent of the project's planting works are complete

7.6 million hours worked by the team since the project began

853,026 native species planted across the project

Supplied A major milestone was achieved for the project at the end of November, with the final concrete pour taking place to complete the 230 metre long bridge deck.