According to the Apple Maps website, Apple has revealed their plans and dates for when they’ll be traveling in order to collect data for its Apple Maps system. “Apple is driving vehicles around the world to collect data which will be used to improve Apple Maps. Some of this data will be published in future Apple Maps updates.”
Given that roads change from time to time and new roads do open up, these are pieces of data that Apple will obviously need in order to keep their maps up to date. It has also been speculated that this initiative could be part of Apple’s plan to create a Street View-like feature of their own.
Several years ago Mark Gurman claimed that Apple had plans to launch a 3D Street View feature of their own, and that they were working on creating a version that is an improvement of what Google offers, so it is possible that Apple’s efforts at collecting data could be leading up to that.