This measure highlights the amount of city roadway that has been rehabilitated each year. Rehabilitation is broken down into three categories: Micro Seal (a thin layer is added to the top of existing asphalt pavement in order to help preserve and protect the underlying pavement structure and provide a new driving surface), Mill & Overlay (a portion of the existing asphalt pavement is removed and a new layer is applied, which can greatly extend the life of the street), and Concrete Reconstruction (when a roadway has failed and can no longer be maintained, the road is completely reconstructed with concrete pavement).