heavy impact these score lines perform another function in permitting alignment of radial legs of the spacer and table if pre assembly is done by cementing the combination prior to final assembly with the outer container fig5 and 6 show a bottom view and cross section respectively of the spacer 40 the spacer 40 is used to elevate the table 16 such as shown in fig9 and 10 in fig9 one spacer is used and in fig1 two spacers are used in addition to maintaining at approximately constant height the center of gravity of the barrier the spacers also reduce the available volume for the dispersible mass 18 of the three barriers shown in fig8 10 the barrier in fig8 is placed closest to the obstruction so that this barrier is the last barrier to be hit the barrier shown in fig1 is placed furthest from the obstruction it is the first unit that is struck by the vehicle the barrier shown in fig9 is placed between the other two barriers as depicted in fig6 the spacer 40 has a height that is reduced from the height of the table 16 each spacer that is used has an outer cylindrical portion 42 and a central hub 44 which is interconnected to the outer portion 42 by a plurality of radially disposed spaced webs.