can be closed with a stopper not shown the inclined ramp speed bump structure of this invention can be fastened to the under layment using only screws 32 holes can be drilled into the ground before assembly the ground usually being strong enough in the case of roadways i e made of concrete or asphalt dowels or like expanding fasteners can be placed in the holes to receive the screws the dowels or the like being forced open when screw 32 is turned down to thereby hold the screw in the concrete or asphalt a force for example of 16 kilo newtons 3600 pounds force for screw 32 is obtained the individual elements of the structure are held down by screws 32 in as complete surface contact as possible between their lower surfaces and the mounting surface in the embodiment shown in the drawings the reinforcement strip 28 has a u shaped profile with a width of about 5 cm each edge of the channel having a height of about half the width the reinforcement strip is made of material of thickness between 8 and 10 mm although prepared screw holes 30 are preferred for connecting channels 28 to the base layer it is possible of course to drill.