Most New Zealand councils compare the grade of driveways on submission documents to the guidelines to gradients in their standards or the national standards typically 1in5 or 1in6. However you may encounter sites that due to the topography cannot be accessed with driveways at these grades.
Raising the question what is the maximum grade a driveway can be constructed at to provide access to a property? To answer this I have measured the grade of a few driveways around town that people seem to be quite happily using. Here are some pictures to assist you with making the extreme happen when you need too. Note Drainage and surface finish are two areas that care need to be taken in as well as ice and snow if this is applicable.