Above is an old image of the Summit Road taken at least a decade ago - a reasonably wide carriageway, not entirely for the faint hearted in places but a grand and very scenic drive around the top of the old volcanic crater rim above Lyttelton and Christchurch.
Images below show one of the the most damaged sections post the 2011 earthquake which closed this section of road for some years and has only relatively recently re-opened to walkers and cyclists.
It would be quite an undertaking to open it to normal traffic again.
Part of the now closed section of road
Interesting (volcanic) geology revealed in this cut.
Below some of the damage to the roads guard rail caused by falling rocks