Mr Troughton said the agency had worked closely with the TEL Tangata Whenua Advisory Group and a Heritage New Zealand archaeologist during construction of the Paengaroa roundabout, because of the site's importance to local iwi and its historic value.
Advisory group co-chairman Dean Flavell said the pa site was once part of a network of waahi marakai (gardening villages) in the Pukaingataru tribal lands.
"It was established during the 1600s, in the times of the Tapuika ancestor, Marukukere," Mr Flavell said.
"The village was defended by stockade, which are represented in the waharoa design.
"The carving depicts Marukukere holding a kaheru [cultivating tool] and kumara while his children are shown in the pou of the palisade.
"The work tells the story of the site and what it was once used for and also welcomes and farewells motorists using the TEL," Mr Flavell said.
The TEL project is expected to be open to travellers by late 2015, while the waharoa was unveiled and blessed on July 23.