The Otira Viaduct in Arthur’s Pass has a 16% grade and curves through the last portion of the pass before Jacksons, New Zealand. January 5, 2016 700 × 467 The Otira Viaduct in Arthur’s Pass has a 16% grade and curves through the last portion of the pass before Jacksons, New Zealand. The Otira Viaduct in Arthur’s Pass has a 16% grade and curves through the last portion of the pass before Jacksons, New Zealand.