rollin wrote:I can see the highway crews now trying to repair roads with imbedded wireless power systems. We can't maintain our infrastructure now and this would make it more expensive to build and maintain.
Roads crack all the time, endure freeze thaw and extreme temperatures. How is the embedded technology going to withstand those problems?
Many roads already have embedded coils in them at intersections to detect when cars pull up to the traffic signal. Granted installing and maintaining an embedded power system in the road sounds much more expensive to both build and maintain, perhaps to the point of being impractical, but it's not like they don't already have some experience building and maintaining embedded coils in the road.
Fully Actuated- All phases of traffic sense cars and respond according to the demand of traffic. Normally, the controller is programmed for maximum and minimum green times. The green light is able to change to red either by serving the maximum time or being gapped out, when there is excessive amounts of time between cars.
How does it sense a car?
When a signal is installed, multiple 6 ft by 6 ft coils of wire are placed under the road surface. These wires are connected to the controller equipment. A small electrical signal is present on the wires and when a vehicle drives over the loops it changes the inductance value on the wire. This change of inductance is recognized as a vehicle presence and the controller acts accordingly.
In the image the coil represents the inductive coil laid in the asphalt. A traffic light sensor uses the loop in that same way. It constantly tests the inductance of the loop in the road, and when the inductance rises, it knows there is a car waiting. When current first starts flowing in the coil, the coil wants to build up a magnetic field. While the field is building, the coil inhibits the flow of current. Once the field is built, then current can flow normally through the wire. When the switch gets opened, the magnetic field around the coil keeps current flowing in the coil until the field collapses.
Traffic LightsAlso, Volvo is experimenting with a slightly different system. Instead of embedding power coils in the road to transmit power wirelessly, they install transfer bars in the road to transfer electricity directly to EVs on the road. Similar to how trams draw power. They claim it is cheaper than installing overhead trolley lines like some buses use.
Volvo sees our future long-haul trucks and buses drawing the juice they need from the road itself, making large onboard batteries a thing of the past. The company is looking at ways to supply constant power to long-haul vehicles from an external source.
the company has constructed a 400 meter (1,312 ft) -long track at a facility in Hällered near Gothenburg, to test a truck fitted with a special collector that draws its power from rails installed into the surface of the road. It's an adaptation of technology that's been successfully used to supply electricity to trams in several cities around the world since 2003, and could help reduce an electric vehicle's dependence on big battery banks.
Elsewhere, companies like Siemens are looking into power delivery using overhead cables, but Volvo suggests that its development may prove a more attractive proposition.
"From what we have seen so far, overhead lines are a more expensive solution than the what we are testing right now," says Johansson. "Overhead lines have the additional drawback that they cannot be used by cars. The visual impact is also less appealing compared to a technology located in the road. But we're not ruling out a solution that uses overhead lines. The research in the coming years will hopefully show what will be best for society."
Volvo's electric roads concept points to battery-free EV futureThe oil barrel is half-full.
