Speed Nudge
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.
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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. You can leave a response, or trackback from your own site.
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June 9th, 2010 at 7:35 am
Neat way to experience this effect at home: just mix corn starch & water in a bowl… if memory serves me well, I think it’s a 50/50 mix by volume. You can poke your finger into it as if water, but try and slap or punch it & it’s like hitting a wall. …This is the same effect as quicksand.
June 9th, 2010 at 7:44 am
(I know everyone says this, but I have to say it)
I thought of this after watching the Mythbusters episode explaining non-Newtonian fluids. Too bad I don’t have a team of physicists to help me implement it.
June 9th, 2010 at 8:42 am
I’m curious how it handles freezing temperatures and bicycle traffic.
June 9th, 2010 at 3:05 pm
It almost certainly has a much lower freezing point (or you could design it to have a much lower freezing point) than regular water. But even if it freezes, the worst thing that could happen would be that it would turn into an old fashioned speedbump. Of course, in that level of cold, you probably should be driving much more cautiously anyway.
June 9th, 2010 at 10:36 pm
I have a better idea, how about a car that tells you when you are going over the speed limit; beeps or light goes off when you are going too fast like when you don’t have your seat belt on.
June 10th, 2010 at 7:49 am
Or even better… use a speed hump/table instead of a speed bump. Why use fancy chemicals when a better-designed vertical deflection could do the same thing?
June 10th, 2010 at 12:35 pm
Here’s an idea - maybe we could put some sort of gauge inside the vehicle that would display the speed the vehicle is traveling? The gauge could be placed just below the windshield so that motorists would always know what speed they were traveling and could thus easily conform to local traffic restrictions.
June 13th, 2010 at 5:29 pm
I’m also curious as to how temperature affects the viscosity. It could be confusing if the speed bump hardened at various temperatures as seasons changed.
June 15th, 2010 at 5:18 pm
Is there anything that works the opposite way i.e. hard at lower speeds/lower weights and fluid at higher weights/speeds?
There are on-going issues with cyclists and LRT or street car tracks - if you could fill the tracks with a non-Newtonian fluid that keeps a cyclist wheel from going into the track and then collapse when the train comes through….