How many coverage passes are typically required when rolling an open graded asphalt friction course?

When rolling an open-graded asphalt friction course, typically only one coverage pass is required. This is because the texture and structure of open-graded mixes allow for effective compaction with a single, adequately executed pass of the roller. The design of these mixes is intended to provide good drainage and skid resistance, which helps to minimize the need for multiple passes that could potentially compact the surface too much or alter its designed properties. Additionally, excessive rolling could lead to issues such as pushing aggregates out of place or causing surface deformation. Thus, the single coverage pass is sufficient to achieve the desired final density and surface quality for open-graded friction courses.