In 1911, that plank road was still use but being replaced. A short blurb in The Fowlerville Review let readers know Redford township was doing just that, obviously pleasing the editor:
Anyone having occasion to drive to Detroit will be glad to learn that a concrete road 16 feet wide will take the place of the old plank road, which has been in a very bad condition for many years past. This new road will extend through Redford township and much of it is already built nine feet wide, but will be extended to 16 and will be completed not later than 1912. The township has sold bonds for $50,000 for the purpose.
I decided to "google" images for a plank road and found a great picture. It came from a page you can read by clicking here.