70 72 to the horizontal members 66 and into the concrete 40 the concrete 40 may be relied upon to provide mass since at impact by a vehicle the bollard sub assemblies 30 may try to rotate and or translate relative to the support surface 20 fig3 b by way of example also illustrates stiffener plates 80 82 84 86 that may extend vertically between and connect to the upper and lower square plates 70 72 during impact by a vehicle the input member 36 may rotate back the stiffener plates 80 82 84 86 may help transfer energy from the upper square plate 70 to the lower square plate 72 see also fig3 a and the horizontal members 66 and the concrete 40 such that this backward rotation may be prevented or at least minimized the stiffener plates 80 82 84 86 are not illustrated in the other drawing figures so as to not otherwise obscure aspects of the invention the bollard sub assembly 30 may be connected to an adjacent bollard sub assembly 30 u2032 by linking members 32 see fig5 and 6 the linking members 32 may be connected to the bollard sub assemblies 30 by bolts 88 or by other devices such as rivets.