"We will not be appealing this decision, as the High Court's decision provides useful clarification on a number of points of law for future infrastructure projects.
"This clarity will be valuable when we, and other infrastructure providers, are preparing for future projects."
Ms Chetwynd said the High Court ruling meant the project would not proceed as the agency did not have the required approvals.
She said NZTA was committed to working together with the community and local councils to spark new conversations and ideas about the best way forward for delivering vital transport improvements for the capital.
Wellington mayor Celia Wade-Brown said there was now an opportunity to explore better transport options at the Basin Reserve.
"In not appealing, NZTA have made the right decision and we will work with them, the Greater Wellington Regional Council and Wellingtonians to create a long term solution including better public transport, urban cycleways, walking and heritage," she said.
"There are a number of opportunities to smooth the flow of traffic and make some time savings.
"Based on the success of the Pukeahu National War Memorial underpass, trenching could be an attractive solution."
