Tangarakau Gorge

The Forgotten Highway is now an unsealed gravel road. Slow down and use the roadside stops to ponder the difficulty facing people whose form of transport was either fast flowing rivers or walking over the rugged terrain. The description “overlooked highway” is apt. Trestle supports the Forgotten Highway Railway Track. Stratford–Okahukura Line is a secondary railway line in the North Island of New Zealand, between the Marton – New Plymouth Line (MNPL) and the North Island Main Trunk (NIMT) Railway, with 15 intermediate stations. It is 144 km (89 mi) long through difficult country, with 24 tunnels, 91 bridges and a number of sections of 1 in 50 grade.

Near Okahukura there is an unusual combined road-rail bridge over the Ongarue River, with the one-lane road carriageway below the single rail track.The line is not currently in service for rail traffic and is under a 30-year lease for a tourist venture, Forgotten World Adventures.

Wikipedia.