This technical paper relates to a device that reduces the speed of any overspeeding vehicles travelling on a roadway.It is formed by at least one hollow strip of flexible material, made up of several receptacles located in the shell body. Each receptacle is impregnated with a dilatant shear-thickening fluid. The material is placed under compression during impact when the vehicle strikes it and the fluid itself acts as means for controlling the resistance to deformation of the strip.Thus, if the vehicle travels at a low speed the fluid has a low viscosity and the strip is easily deformed, whereas if the speed of the vehicle is high the viscosity of the fluid is high and as a result has great resistance to deformation, thus forming a rigid obstacle to the passage of the vehicle. Drivers must always slow down when driving over the conventional speed bumps to prevent damage to their vehicle. However, the Variable Density Speed Hump is sensitive to the speed of the vehicle.The vehicle needs to slow down only if it is overspeeding.