The dual cycling and tramping trail, part of the New Zealand cycle trail, follows historic gold miners' roads from Lyell in the upper Buller Gorge and down the Mokihinui River to Seddonville.
It takes in the abandoned settlements of Zalatown and Gibbstown.
"Once fully complete, Old Ghost Rd will offer a challenging multi-day ride or walk through some of our more remote backcountry, covering native forests, open tussock tops and isolated valleys with views of the spectacular Mokihinui Gorge," Dr Smith said.
The trail is being developed by the Mokihinui-Lyell Backcountry Trust, in partnership with DOC and community and business groups.