The verdant Manawatu Gorge is a striking stretch of state highway.
It's a treacherous beauty, whereby drivers give in to the scenic temptation to gaze at a waterfall or two, fierce green rapids or turgid bush akin to hundreds of giant broccoli heads thrust from a vertical garden.
Anyone lucky enough (like me) to have rafted the river below will know the view from the fast-flowing Manawatu is outstanding.
Records show the road was completed in 1872, with the rail track added to the opposite side of the gorge 19 years later.
The gorge, or Te Apiti, translated means "The Narrow Passage". Which, of course, is at the heart of the problem. Its alpine contours shoulder a thin track prone to erosion.