more suspicious energy harvesting projects for roads!

[tron9000]

http://phys.org/news/2011-11-speed-bump-device-traffic-energy-electricity.html

This video's a pearler - how do you kow the cars not driving over a button connected to a MCU that's flashing the lights 

Someone threw and idea at me of using a hydraulic "button" to compress hydraulic fluid through a generator from a car rolling over it. Something just doesn't sound right about that.

[AndyC_772]

There's no need to 'cheat' in terms of using an external supply to power the lights. You really can obtain useful energy this way.

Unfortunately that energy is anything but "free"; it comes from the car's engine, which has to lift the car up and over a bump which wouldn't otherwise be there. If you doubt that this requires energy, just try pushing a car first along a flat surface, and then up a low kerb.

[grumpydoc]

You beat me to a reply but agree 100%

More than it not being free, it would be an extremely inefficient use of fuel, most carbon un-friendly.

[tron9000]

oh I agree that's its not free, your spending fuel and therefore money getting up the hump, and true the video doesn't have to cheat but it doesn't lend itself any favours by not showing " there's nothing up my sleeves!"

Plus I think its more specific to speed bumps rather than say them being limed along the motorway.

[G7PSK]

If you have to have a speed bump any way you could use this to work a speed sign, but the costs have to far outweigh a solar cell and the maintenance will be far greater as well.

[Halcyon]

All well and good, except in Australia, people largely drive around or avoid speed humps where possible.