as will be later described each belt 22 is located within suitable belt receiving connectors 24 that are connected to the base bar 14 and to the reclining bar 16 and prevent sliding of the belt 22 toward the activating pivot 18 the modular unit 12 is provided with a receiving ramp 26 in a forward portion 28 of the modular unit 12 the receiving ramp 26 is slanted forwardly thus enabling to receiving thereon a wheel of a threatening vehicle in a case that the wheel rolls on the receiving ramp 26 and not to the sides thereof the modular unit 12 is provided in a rearward portion 30 thereof with a rearwardly and downwardly pointing heel 32 that protrudes downwardly from the base bar 14 and helps inserting and affixing the barrier 10 into ground 34 in a case of a collision by a threatening vehicle a plowing projection 36 protrudes rearwardly and downwardly from the reclining bar 16 in an active position of the modular unit 12 a horizontal reclining bar 38 is pivotally connected to the base bar 14 adjacent the forward portion 28 of the modular unit 12 and near a top portion of the receiving ramp 26 the horizontal reclining bar 38 is secured to the base bar 14 in a folded position by means of a horizontal quick locking pin 40 a vertical reclining bar 42 is pivotally connected to the reclining bar 16 adjacent an upper end 44 of the reclining bar 16 the vertical reclining bar 42 is secured to the reclining bar 16 in a folded position by means of a vertical quick locking pin 46 in order to assemble the barrier 10 the modular units 12 are placed on ground 34 parallel to each other and spaced apart.