Road closures along New Zealand's highway network can have significant impact on traffic and freight movement. Identifying approved diversion routes before incidents occur, allows NZ Transport Agency to efficiently divert traffic away from problem areas. While many diversion routes have already been identified throughout the highway network by NZ Transport Agency, some routes are maintained in paper reports only. These sections needed to be migrated into a digital format to ensure that a single spatial dataset has the most up-to-date diversion routes.


NZ Transport Agency's geospatial team collaborated with Interpret to identify the best solution. After reviewing the paper based detour routes, Interpret identified those that were missing from their digital counterpart. These routes were digitised using an underlying road dataset and appended to the existing detour network. Once the spatial geometries were captured, relevant route information could be derived for each alternate route. For example, an estimate the total travel time of a given detour, the different road surface types intersected and whether the route was suitable for heavy vehicles.


Mapping the existing diversion routes across the country allows NZ Transport Agency to efficiently respond to highway closures and minimise travel delays. The digital dataset can be queried and analysed and GIS provides a suitable platform for maintaining ongoing updates. The NZTA can also repeatedly examine the network for problem areas. These may be sections where approved detour routes have not yet been identified or ‘high-risk sections’, where no viable detour routes are available.

For more information, contact:
Daniel Nutsford
+64 9 281 2186
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