A Spanish company, Badennova, has developed what it calls an “intelligent speed bump,” which only acts as a speed bump if you’re going faster than the posted speed:
When vehicles traveling at the appropriate speed pass over the top, the intelligent speed bump provides no resistance and, as a consequence, does not cause any damage. For cars moving at excessive speed, however, the speed bump hardens and therefore provides the same resistance as any standard speed bump.
This behaviour is due to a non-Newtonian fluid which constitutes the filling material of the intelligent speed bump. These kinds of fluids behave differently than water. This means that their flow properties cannot be described by a single constant value of viscosity. There are different types of non-Newtonian fluids. The intelligent speed bump contains a so-called shear-thickening fluid (also known as dilatants).
Dilatants are suspensions whose viscosity increases with the rate of shear, i.e., the strain rate raises with the rate of shear. The dilation effect occurs when closely packed particles are combined with enough liquid to fill the gaps between them. At low velocities, the liquid acts as a lubricant, so the non-Newtonian liquid flows easily. At higher velocities, the liquid is unable to fill the gaps created between particles, and friction greatly increases, causing an increase in viscosity.
As a consequence, the non-Newtonian material allows the speed bump to change from a soft to a solid state according to the vehicle’s speed.
This entry was posted on Wednesday, June 9th, 2010 at 7:15 am and is filed under Traffic Engineering, Traffic safety. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.