Frontier-Kemper has a long history of designing and excavating tunnels using the cut-and-cover (or open cut) tunneling method. This is the oldest method of tunneling excavation. It involves digging a trench, installing retaining walls, installing horseshoe-shaped ribs/lagging (if applicable), constructing the tunnel, and returning the surface back to normal. This approach is more economical and ideal for shallower tunnels and when the conditions permit. We have extensive experience in top-down and bottom-up cut-and-cover methods in both the heavy civil and mining industries.