Bolts provide support to the roof and rib of roadways by clamping the layers of strata together. Bolts come in varying lengths and design types to suit the specific geology of the rock mass in the roof or rib. To install a bolt, a hole is firstly drilled to the required length into the roof to allow for the insertion of the bolt. Once inserted the bolt is either mechanically or chemically anchored in place.The bolt head will protrude from the hole to allow a plate and nut to be tensioned. The bolts also provide anchor points to support roof bars, mesh, and girders.