James Careless looks into the ‘smart’ and energised future of the world’s highways.
SOLAR-POWERED self-lighting roadways, with induction lanes that charge electric cars as they drive.
Asphalt pavement that stores solar energy, using it to melt off snow and ice when the temperature drops … or perhaps that energy can be used elsewhere to heat buildings? And if that’s not enough, how about harnessing the physical flexing and releasing of asphalt pavement caused by passing traffic to generate electricity?
These are just some of the futuristic ideas for the asphalt highway of tomorrow, now under development today. Here’s a closer look:
The incredibly ‘smart highway’
Back in the 1980s, the ‘Intelligent Highway’ concept was all the rage. But the advances then being proposed focused on making cars more intelligent in the operation; the roads remained the same.
Fast forward to today: Designer Daan Roosegaarde and Dutch construction firm Heijmans have banded together to create the ‘Smart Highway’ a series of projects where the road – not the car – does more than just sit there. A case in point: The ‘Glowing Lines’ concept employs light-emitting marker lines that are recharged by the sun during the day, and emit light for up to 10 hours at night. This isn’t vaporware: As of April 2014, two 500 metre long stretches of the N329 provincial highway near Oss, Holland, have been equipped with Glowing Lines.
Roosegaarde has lot of other exciting highway ideas that he and Heijmans are developing into working prototypes. For instance, the Electric Priority will recharge the batteries of electric cars driving on it, by transferring energy wirelessly to the car through magnetic currents. (Magnetic ‘transmitter coils’ within the roadway will induce power generation in a magnetic ‘receiver coil’ inside the vehicle car, which will transfer this power back to the car’s battery.)
Meanwhile, temperature-sensitive ‘dynamic paint’ can be used to make illuminated warnings visible only when relevant. For instance, when the outside temperature gets close to a freezing point on a bridge, a dynamic paint warning about potential slippery conditions can appear.
Roosegaarde’s ideas for Smart Highways don’t end there. They include addressable ‘Dynamic Lines’, which can be remotely triggered to show either solid or dotted lines depending on the amount of road traffic – and interactive street lamps that only come on when cars approach – and can flash when cars are going too fast. As for all that wind generated by passing cars, Roosegaarde envisions using that moving air to spin small wind turbines along the curb; creating the power to illuminate the shoulders at the same time.
“Daan Roosegaarde was amazed that we spend so much time and money on the technology of cars, yet the highway has not changed for the last 100 years,” explained Jamaica den Heijer, Studio Roosegaarde’s director of business development. “He presented all of these ideas when he gave a lecture, and the director of Heijmans, a large construction company in the Netherlands, was present and contacted Daan afterwards. Then they met and the Smart Highway project was born.”
Capturing roadway heat
There’s nothing like a mid-summer barefoot stroll across South Las Vegas Boulevard (home of the Las Vegas Strip) at noon to reinforce the point that sunlight makes asphalt pavement hot! But making this heat actually do something beyond scorching your feet; now that’s a challenge!
A British firm called ICAX (www.icax.co.uk) has developed a way to do just this; specifically to transfer the heat energy captured by sunlit roadways and then transfer it to “thermal banks”. This is done by installing a network of fluid-filled pipes under the road. The asphalt’s heat is transferred to the fluid, which is then pumped into tubes buried under insulating earth. The dirt retards the heat loss; providing a reservoir of heat that can be extracted by buildings equipped with heat pumps during times of cold weather. ICAX calls this concept “Interseasonal Heat Transfer” (IHT).
Beyond providing buildings with low cost heating, IHT can be used to rewarm roadways during winter, by pumping the thermal banked fluid back into the under-roadway pipes. The released heat can melt snow and ice on an ongoing basis; keeping roadways clear even during snow storms.
“This concept is already in use at Heathrow airport, to keep the tarmac clear of ice and snow all year round,” says Dr Heather Dylla; director of sustainable development at the National Asphalt Pavement (NAPA) in Lanham, Maryland. “It is a powerful demonstration of how much can be done with asphalt paved surfaces when a creative engineering approach is applied.”
A similar concept has been tested by the Worcester Polytechnic Institute in Massachusetts. They placed a pipe network just below an asphalt pavement, and filled it with water. The asphalt transferred heat to the fluid, which was then available as a hot water source or to generate electricity. A bonus: Extracting heat from the roadway helps prolong its life span, by reducing cracking due to expansion and contraction.
The astounding energy-generating roadway
Asphalt Pavement 101: Paved roadways vibrate as cars and trucks drive over them. What if all that vibrational energy could be somehow harnessed; perhaps to generate electricity, for instance?
This concept is not only possible: It has already been proven. A 2011 pilot study into roadway “vibration energy” generation by Holland’s University of Twente and the Dutch province of Overijssel used piezoelectric roadway materials to convert vibrations into measurable power. Basically, the ongoing compression and decompression of piezoelectric crystals in the roadway material generates electricity.
The University of Twente study, which used a piezoelectric embedded strip across the N34 provincial motorway near Hardenberg, showed that enough energy could be generated to power wireless motion detectors to trigger stoplights. The 2013 paper “Piezoelectric Roads in California” written by Stanford University’s student Rex Garling (large.stanford.edu/courses/2012/ph240/garland1/; cited by NAPA) estimated that a 20mpg car using $4/gallon gas on a one kilometre stretch of piezoelectric-equipped roadway would generate about 0.19MJ of electricity. Based on current West Coast electricity charges, this would be about 1/20th of the gasoline cost burned to cross this length of roadway.
“At this rate, the road will generate a revenue of $33,565 per year,” Garling wrote.
A solar option
Imagine lining a roadway in part, or in full, with hexagon-shaped solar-powered road surface ‘panels’ loaded with LEDs. Depending on how they were configured, these ‘solar road panels’ allow sunlight through their textured glass surfaces and into their solar collectors by day, and then use it to light road markings at night. They can also heat themselves to remove ice and snow as needed (via built-in heating and drainage elements), and perform a number of other power-related tasks; such as creating illuminated ‘crosswalks’ 24/7.
This is the idea behind Solar Roadways (www.solarroadways.com). Spearheaded by electrical engineer Scott Brusaw and his wife Julie, the Solar Roadways project has received funding from the US federal Highway Administration for both its Phase I and Phase II prototypes. They’ve raised US$2.2 million on the Indiegogo.com crowdfunding campaign site for their project; not bad considering that the Brusaws were only asking for US$1 million. Currently, Solar Roadways is about to complete its Phase II project by paving a prototype parking lot with its solar road panels.
The beauty of solar road panels is that an entire road does not have to be paved with them. Instead, they can be integrated with existing asphalt pavement construction; providing cutting-edge capabilities in tandem with the proven durability and cost-effectiveness of asphalt pavement.
The roads of the future are coming
The ideas described above illustrate how much is being done today to advance the functionality of tomorrow’s roadways. As the proven experts in road construction and science, members of the asphalt industry are ideally placed to capitalise on these advances, and to marry them with the many improvements in asphalt paving (eg, warm mix asphalt, reclaim asphalt pavement recycling) that the industry has already pioneered.
“There is a lot of research being done to capture and store energy from roads,” says NAPA’s Dylla.
“It will be interesting to watch them advance and to see how the science is put into practice.”