Components The sinkhole protection system consists of standard reinforcement steel strands functioning as linear bearing elements and a high-tensile, diamond-shaped steel wire mesh functioning as a flat force spreading element. Dimensioning When using the ERFA system, the thickness of the spoil plus the combined binder and top layers is relatively small compared with the sinkhole diameter. As a result no load bearing arch can form. Corresponding to the break-in model the total applied load is to be carried through the membrane. The resulting forces are to be transferred laterally in the road longitudinal axis. The ERFA system possesses pronounced anisotropic characteristics and as a result can be dimensioned for the level case according to the membrane theory. Tests To verify the functional suitability of the ERFA system, full-scale 1:1 field tests were carried out. Placed first was an asphalt load bearing layer and secondly a concrete slab with thickness of 20 cm and width of 2.5 m. The modeled sinkhole exhibited a rectangular hollow with a free span width of 3.0 m. With both test set ups, a total loading of 30.4 tons resulted in a depression in the slab center of approx. 20 cm. The ERFA system showed considerable reserves to be available. Installation The ERFA sinkhole protection system is installed in the loose stone layer below the first bituminously or hydraulically bonded layer or the concrete supporting layer. Expenditure on earthwork in particular with restorations or in cuttings is kept to a minimum. The dimensioning concept is adapted accordingly.