fig1 illustrates a solid concrete element 1 in an end view from which appears that the end face of the block 1 is formed with a recess or notch 2 in which is arranged a coupling element 3 in accordance with the invention . fig2 illustrates the coupling element 3 in accordance with the invention in a lateral view , the element as illustrated comprising two t - shaped sections 4 , 5 with legs 6 , 7 . the legs 6 , 7 ( see also the plan view of fig3 ) are intended to be secured in the concrete block 1 by being embedded therein during the casting of the block in such a manner that the cross - bars 4 &# 39 ;, 5 &# 39 ; of the t - shaped sections , which cross bars extend at right angles to the legs 6 , 7 , will be positioned opposite one another , when two concrete blocks are positioned essentially end - to - end . a tube 8 is then used to lock the two vertical cross - bars 4 &# 39 ;, 5 &# 39 ; to one another . for this purpose it is also possible to use a tube 8 &# 39 ; which , as indicated in fig1 is anchored to the ground 9 , although naturally it is also possible to pass a tube 10 into the recess 2 from above , as indicated in fig4 . in the latter case , the tube 10 may be utilised as a support of e . g . signs , such as a road sign 11 . as illustrated in fig5 the concrete block 1 may be made hollow , however with sufficient thickness of the side walls 12 , 13 to ensure adequate strength of the block . in addition , care must taken to ensure that the base portions 14 , 15 of the walls 12 , 13 are sufficiently thick to house a coupling element 3 in accordance with the invention , one such element being inserted in the manner indicated in a suitable semi - circular notch in each one of the end walls of the block 1 . fig6 illustrates the coupling element proper on an enlarged scale and in an exploded view , the legs 6 , 7 of the t - shaped sections 4 , 5 intended to be cast into the blocks 1 in notches 16 , 17 formed therein in such a manner that upon interconnection of two blocks placed in end - to - end positions , the t - shaped sections 4 , 5 will assume the positions indicated in fig2 . when two blocks are placed in end - to - end positions and the coupling elements thus assume the position illustrated in fig2 the latter may easily be interconnected by a tubular piece 18 which is passed over the vertically directed cross - bars 4 &# 39 ;, 5 &# 39 ; of the t - shaped sections 4 , 5 . blocks 1 interconnected in the manner indicated in fig5 i . e . at their base portions may be suspended in rods 19 anchored in the ground 9 and when interconnected by means of coupling elements in accordance with the invention the blocks will be slightly tiltable . fig7 illustrates blocks 1 which are suspended from a rod 20 by means of a suspension arrangement which differs from the one illustrated in fig5 . in this case the blocks are provided with loops 21 by means of which the block may be suspended in hooks 22 arranged on the rod 20 , the latter being anchored in the ground 9 by means of vertical rods . fig8 illustrates in end view a block 1 including a loop 21 and coupling elements 3 . also in this case the resulting barrier is somewhat yieldable . in some cases it may be desirable that the concrete block projects to one side only and one example of a block of this kind is illustrated in fig9 this figure showing an end view of a block 1 formed with one single side wall 23 the base portion 24 of which is formed with a recess 25 for introduction thereinto of a coupling element 3 in accordance with the invention . this block 1 is provided with a loop 21 for suspension in the manner described with reference to fig7 . to ensure that the block assumes the desired position it is preferably formed with a balance weight 26 . the upper part of the block may have the configuration indicated in fig1 , which makes it possible , by arranging two blocks in mirror - image position , to interconnect the blocks 1 , placing notches and projections formed at the upper part thereof in interdigited positions , whereby when two such blocks are interconnected a combined block is obtained , having essentially the appearance illustrated in fig8 . in accordance with one aspect of the invention illustrated in fig1 a bulb rail 31 is provided , which may be formed by bent or extruded sheet metal or plastics . fig1 illustrates the upper part of a concrete block 32 on the upper face of which the bulb rail 31 is intended to be applied . for this purpose the block 32 is provided with retainers 33 intended for insertion into grooves 34 or 35 formed in the bulb rail . in the case of the groove 34 the bulb rail 31 need only be slided endwise to the desired position whereas in the case of the grooves 35 , the bulb rail is passed over the retainers 33 and is then slid lengthwise to the desired position . the arms 36 of the retainers 33 are designed to press resiliently against the inner face of the bulb rail 31 in such a manner that the latter is secured in position against the upper face of the concrete block 32 . in fig1 and 15 are shown the surfaces of respectively the bulb rail 31 and the concrete block 32 that are to be attached to one another . although fig1 shows grooves 34 as well as grooves 35 it should be obvious to the expert in the field that when the bulb rail 31 is formed with the grooves 35 the groove 34 need only be shaped to allow slight displacement of the bulb rail 31 , allowing the arms 36 on the retainers 33 to press against the inner face of the bulb rail 31 adjacent the grooves 35 . obviously there is nothing to prevent designing the bulb rail 31 in the manner indicated in fig1 , if such a combination were preferable . fig1 and 17 show the ends of the bulb rail 31 . as indicated in the drawings , these ends are biased and preferably non - symmetrical in order to prevent vehicles that drive up onto the concrete block from catching in this edge . in this connection should be pointed to the provision of an opening 37 , corresponding to the notches 38 in the end faces of the concrete block 32 and intended to house and retain e . g . rods carrying traffic or road signs and the like . in this connection deserves mentioning also that the hollow bulb rail 31 makes it possible to draw electrical wiring and cables therein in a safe and protected position to road signs that should be illuminated . in fig1 is shown a clamping member 39 , made from sheet metal or plastics , intended to be clamped over the joint between two bulb rails 31 placed in end - to - end position and to be retained in this position by its inherent resiliency . the clamping member 39 is provided with a pin stub 40 intended to be inserted in the opening 37 , e . g . through clamping action . fig1 , finally , shows a concrete block 32 which is provided on its lower face with shafts 41 supporting rollers 42 whereby displacement of the block 32 is facilitated . on account of the immobilising effect obtained through the bulb rails 31 applied on the upper face of the block 32 , which bulb rails need not have an even length with the concrete block 32 , the blocks 32 may be fitted with these rollers 42 which facilitate displacement of the block , particularly in the non - interconnected position thereof . prior - art blocks have required provision thereon of leg sections , making it possible to insert the fork members of e . g . a forklift truck underneath the block in order to move the block . the bulb rail 31 could of cause be given many other shapes than the one illustrated , provided it prevents cars from passing over the concrete block and onto the roadway at the opposite side of the block . in addition , the rail should have a configuration that eliminates the tendencies of the car to wobble and it should guide the car softly back onto the roadway . without detailed explanations it should be obvious to the expert that a variety of shapes of the bulb rail could serve this purpose . in addition , the bulb rail 31 is preferably provided with apertures 43 in which could be applied e . g . lamps . rubber pads could be inserted intermediate the end faces of adjoining blocks , if desired . the invention is not limited to the embodiments as shown and described but various modifications are possible within the scope of the appended claims .