Big World: Making roads work harder
In the future, roads will no longer be simple slabs of tarmac or concrete. They will be multi-purpose and productive.
South Korea started to incorporate multiple uses into their roads in 2013 when the Korea Advanced Institute of Science and Technology (KAIST) developed roads that could wirelessly charge specialised electric vehicles. The pilot project installed electric cables into a road underneath a bus lane in Gumi City, Central Korea.
“The magnetic field generated from the power supply line is sent to a pick-up device attached to the lower part of the vehicle” describes Professor Dong Ho Cho, Professor of the School of Electrical and Electronic Engineering at KAIST and Project Director. “The pick-up converts received magnetic field to electrical energy, which drives automobile motors, and remaining energy is charged to the battery. In the area where there is no power supply line, OLEV bus uses electric energy stored in the battery”. Continuous wireless charging reduces the bus’ battery size by two-thirds – cutting the cost of the one of the most expensive parts of the vehicle. Since the 2013 pilot, investigation into OLEV technology has been taken up by researchers globally. Professor Cho predicts that “most vehicles will use wireless charging in the future.”
In 2018 a similar multi-function roadway opened in Jinan, China. This time harnessing solar energy. Photovoltaic panels are embedded between a layer of insulation at the bottom, and a layer of transparent concrete at the top. The top layer has the structural properties of bitumen and the transparency of clear glass, so it can be both load-bearing and allows the PV panels to charge. The road is said to be able to bear 10 times more pressure than normal asphalt. As well as charging electric cars with OLEV technology, the road is ambitiously billed as an energy producer for nearby industry and said to generate 1 million kWH of electricity – enough for 800 households.
Back in Australia, a research lab from the University of Melbourne is also developing multi-purpose roads. Here, the secondary purpose of roads is to recycle rubber tyres. Australia has huge deluge of 51 million tyres discarded annually which, without adequate recycling facilities, mostly end up in landfill or hazardous dumps.
A research team directed by Dr Madhi Miri Disfani is revolutionising pavements (and potentially roads) to be made from the composite materials of granulated rubber tyre, highly processed clean-cut rock and polyurethane binder. The result has the right balance of rigidity and flexibility for low-level load bearing such as bike lanes and pedestrian walks. Its surface allows water run- off to permeate the pavement, which mitigates road flooding, watering nearby trees and eventually replenishing underground water tables.
The pilot project logged a better rate of water infiltration, and a lower level of clogging, than similar materials. Tyres are also cheaper, lighter and more readily available than the usual rubber component used in similar pavements. “There is just so much potential here, ”says Project Director, Dr Disfani. One square-metre of pavement uses up to three car tyres. “Even if you replaced 5% of pedestrian walks in Melbourne, you can imagine how many tyres you will get off the landfill.”
Global solutions to energy, transport and environment problems now have to be multi-faceted. The future is made up of multi-purpose materials that meet more demands than one.