Waka Kotahi NZ Transport Agency systems design regional manager Kesh Keshaboina said preliminary work was able to be combined with routine road maintenance last month.
"We were able to incorporate our pavement preparation with recent regular maintenance work.
"Our state highway maintenance team laid the asphalt base of the new crossing overnight in April, while they were carrying out road resurfacing in the area."
This means the road won't have to be dug up to construct the crossing, reducing overall disruption.
Work will start on the city-bound side of Cobham Drive, with traffic reduced to one lane during off-peak periods.
The new crossing is expected to open in late October.
Safer speed limits are already in place between the Mt Victoria Tunnel and the Airport.
The crossing will only operate on demand. Signal sequencing will be staggered so that traffic on one side of the road is not interrupted by a person crossing the other side.
If no one is using the crossing, vehicles will not be required to stop.
On announcing the airport was no longer pursuing legal action, new chief executive Matt Clarke said it was time to move on and focus on the bigger transport issues for Wellington.
"Prolonged legal action won't benefit anyone now that construction has been allowed to begin."
Clarke said he still thought an overpass would have been a better and safer solution, which was supported by Wellingtonians and businesses.
LGWM has previously committed to investigate whether an alternative option, such as a bridge or underpass, may be suitable as a long-term option for people to cross Cobham Drive.