It seems that this technique would pull kinetic energy off the vehicles that pass over it, causing them to use more gasoline to maintain their speeds. Hundreds of small ridges or ditches that must be traversed by the vehicle will make for more road resistance than with a smooth road. That would result in the relatively inefficient gasoline engines being effectively used as generators. However, if the system were used in pedestrian traffic areas, this would not be a concern. Most people could use the exercise anyway.

It sounds like it would make the road kinda bumpy, plus the maintenance headaches with leaks and lots of moving parts. But perhaps you could somehow use a pezio-electric material for the roadbed and somehow harness the power, perhaps to run a localized system like the traffic lights.

Another expensive possibility might be to replace overhead lighting on highways with very efficient LED lighting embedded in the highway. These lights could be energised by piezo- electric actuators in the roadway that would not require any bumps in the highway. The lights actuated would only be those preceding the vehicle for a useful distance outlining the divider line and the edge of the pavement. The lights could be varied in color if there was any special danger ahead and might blink if a crossing or some other hazard were approaching.

I heard they did something like this at Grand Central Station in NY: piezoelectric floor tiles generated electricity. However, it would be less practical for roads, because cars do not step, they roll, losing far less energy to the ground. The technology is only practical for pedestrian areas, especially crowded ones. It would work in a stadium or shopping mall, though.

I thought of this idea too, thinking about all the cars zooming down the road contributing nothing. It would need to be constructed without moving parts etc, just some kind of pressure plate that would be pushed on and released everytime a tire passed over it. There would be no ridges or noticeble features. An even more whimsical idea would be an "energy harvestng" tunnel to somehow make use of all the moving air generated by vehicles. "MAINTAIN LANE, APPROACHING ENERGY HARVEST TUNNEL, REMOVE SUNGLASSES"

johncalusa's post explains why this is not a good idea.
You can't get energy from nowhere. In this case you would be increasing the rolling resistance for the vehicle - similar affect to a headwind - and the engine would use more power. You would be "stealing" energy from the moving vehicle.
Fuel consumption would go up. The car owner would be paying for this in higher fuel bills.

Since vehicle engines are not the most efficient - and you would get more losses in your conversion method, it would be more efficient to use the fuel directly in a power station.

Actually, I think embedding a power generation system in roadways is conceivable, but he is just talking about the wrong energy conversion process. If simple pipes were put in roadways with insulated tanks on the sides of roadways, local housing and industry could tap into the heat absorbed by those roadways.

For instance, if a small electric pump turned on every time the roadway fluid became warmer than the fluid in the tank, the fluid in the tank would heat up. At night when the roadway cools, the pump would stop when the tank temperature equaled the roadway fluid temperature.

On demand, local housing would start a small pump from their heating system to draw heat off of the tank to help keep their home warm at night; or even the day if the tank is large enough and the Summer heat excavation exceeded the Winter utilization.

Roadways are a significant source of power.

However, the thermal expansion of pipes won't be the same as the pavement, so lots of damage would ensue unless significant forethought was put forth in the engineering design.

The guy who said that you can't get energy from no where is right, but how about making each car carry magnets and installing conducting wires in the road. The reinforced concrete could perhaps be modified to incorporate this design.

I believe that a magnetic field passing through an conductor will generate a current. This current can then be bled via feeder wires into the national grid.

Have each car carry magnets???

What a great idea. That way all the screws, nails, and other ferrous debris on the road could get picked up by the first passing car. Brilliant, just brilliant. Just think of the flat tires this would prevent. Just think of the jolt you're going to get passing over railroad tracks and manhole covers, tho'.

Moving objects typically create wind. Ever have a semi blast past you when you are stopped on the side of the road? How about wind produced by autos traveling down the road turning some type of turbine generator(s)?

I had same kind of idea long back. Yes it is doable by using energised by piezo- electric actuators. Think of vibration generated without having any additional fitting to existing vehicles. Think of vibration adjacent to Railway tracks. Why not generate energy out of it.

Yes feasibility study has to be done properly. God to have any kind of energy genration when entire world is starving for Energy.