There are a lot of factors that can lead to road closures or diversions, from weather issues to road works or road maintenance. Always check road & weather conditions before starting a new day on your road trip through New Zealand.
How to know about upcoming road works & closures? Easy, these are the most important sources of info.
Online: Waka Kotahi / New Zealand Transport Agency - NZTA - Highway Conditions Overview
Road trip app: recommended Free Camping & Road Trip Apps
The NZTA Journey Planner is a great tool to plan your road trip and see if there are issues to be expected on your preferred route.