A multiple necked-down breakaway coupling for a highway and roadside appurtenance to be mounted on a base, the coupling defining an axis and comprising: - a controlled breaking region arranged along said axis and having opposing axial ends; - first connecting means for connecting one of said opposing axial ends to the highway or roadside appurtenance; - second connecting means for connecting another one of said opposing axial ends to the base on which the highway or roadside appurtenance is to be mounted. - at least two axially spaced necked down (16, 18) portions coaxially arranged between said opposing axial ends of the controlled breaking region; - two axially aligned conical portions (60, 62, 64, 66), arranged on the necked down (16, 18) portions, inverted one in relation to the other and generally joined at their apices to form a generally hour-glass shaped configuration having a region of minimal cross-section at an inflection point having a gradually curved annular concave surface defining a radius of curvature, each of said two necked down (16, 18) portions having different radii of curvature at respective inflection points (16', 18') to provide different failure modes as a function of the position and direction of impact of a force on the appurtenance, wherein the controlled breaking region has a minimum ultimate tensile strength from about 53.8 kN to about 221.5 kN, and wherein said maximum ultimate restrained shear strength is from about 5.8 kN to about 24.5 kN, and wherein said maximum ultimate restrained shear strength is within the range of about 6% to about 12% of said minimum ultimate tensile strength, and wherein the radius of curvature R1 of one necked down (16, 18) portion is approximately 0.3175 cm (0.125 inches) and the radius of curvature R2 of the other necked down (16, 18) portion is approximately 0.48 cm (0.2 inches), characterized in that - the controlled breaking region is a steel alloy that comprises about 0.4% carbon at the minimum, about 0.7% to about 1.10% manganese, about 0.15% to about 0.35% silicon, about 0.8% to about 1.20% chromium, and about 0.15% to about 0.25% molybdenum and the microstructure of said steel alloy is substantially acicular ferrite and fine pearlite, and said steel alloy has a fine grain size of about 5 to about 8. - a controlled breaking region arranged along said axis and having opposing axial ends; - first connecting means for connecting one of said opposing axial ends to the highway or roadside appurtenance; - second connecting means for connecting another one of said opposing axial ends to the base on which the highway or roadside appurtenance is to be mounted. - at least two axially spaced necked down (16, 18) portions coaxially arranged between said opposing axial ends of the controlled breaking region; - two axially aligned conical portions (60, 62, 64, 66), arranged on the necked down (16, 18) portions, inverted one in relation to the other and generally joined at their apices to form a generally hour-glass shaped configuration having a region of minimal cross-section at an inflection point having a gradually curved annular concave surface defining a radius of curvature, each of said two necked down (16, 18) portions having different radii of curvature at respective inflection points (16', 18') to provide different failure modes as a function of the position and direction of impact of a force on the appurtenance, wherein the controlled breaking region has a minimum ultimate tensile strength from about 53.8 kN to about 221.5 kN, and wherein said maximum ultimate restrained shear strength is from about 5.8 kN to about 24.5 kN, and wherein said maximum ultimate restrained shear strength is within the range of about 6% to about 12% of said minimum ultimate tensile strength, and wherein the radius of curvature R1 of one necked down (16, 18) portion is approximately 0.3175 cm (0.125 inches) and the radius of curvature R2 of the other necked down (16, 18) portion is approximately 0.48 cm (0.2 inches), characterized in that - the controlled breaking region is a steel alloy that comprises about 0.4% carbon at the minimum, about 0.7% to about 1.10% manganese, about 0.15% to about 0.35% silicon, about 0.8% to about 1.20% chromium, and about 0.15% to about 0.25% molybdenum and the microstructure of said steel alloy is substantially acicular ferrite and fine pearlite, and said steel alloy has a fine grain size of about 5 to about 8.