Roads that can repair themselves - hi-tech highways of the future

The road will be able to monitor its own condition using sensors embedded in it. These will detect potholes and sub-surface cracks, and relay the information to a control centre. These same sensors will receive information from cars, which, as they pass over the damaged road, will be able to report adverse wheel and suspension movements.

Meanwhile, scientists at Delft University in Holland are developing concrete additives that rejoin and reseal the road’s base when it cracks under pressure. Another of their trials involves blending steel fibres with the concrete. As the road ages and becomes brittle, the fibres could be heated by an electric current, restoring the road’s suppleness and prolonging its life.

Roads will be able to clean themselves, too, by using an ultra-smooth surface that will allow grit to be easily washed away. Being hydrophobic, it will also repel water.

Road salt could be made a thing of the past. Pipes located just below the road surface and containing a special fluid could be heated by the sun. At night, the heat would be released to keep the road clear of ice. Alternatively, the liquid could be cooled to prevent extreme sun damage to the road in the summer.

The surface will also be highly reflective, making the road and the immediate area brighter, so roadside lighting could be dimmed or removed, while interactive lighting would only come on when it sensed traffic approaching.

Moves are already afoot in Holland to remove the need for conventional lighting. On a 600-metre stretch of road in the city of Oss, so-called ‘glowing lines’ on the road surface, which absorb light during the day and release it at night for up to eight hours, have replaced traditional street lights.

Powering the roads of the future is also exercising the transport scientists’ minds. The boffins at Delft are trialling a surface made of solar cells which could power all manner of services, including the next generation of LED road studs. Studs are currently used to delineate lanes, but they could also change colour to signal when a car is travelling too close to the one in front.

Another idea involves turning roads into power stations. Tiny piezoelectric generators (PEGs), which turn mechanical energy into electrical energy, could be embedded in the asphalt where vehicle loads are greatest. The PEGs would be connected to the grid and the power used to heat homes or even recharge electric cars. Other ideas for harvesting energy include recovering heat from braking wheels.

Easily the most intriguing feature of Collis’s fifth-generation road is the role that sensors could play. Not only would they be able to monitor the road’s health along with weather and traffic conditions but they’ll also be able to change the behaviour of cars passing along it.

Imagine there’s been a serious incident with cars braking en masse to avoid a pile-up. Sensors in the road will be able to communicate this to the car, in turn influencing its steering, braking, suspension and engine management systems to bring it under progressive control. They could also influence a car’s general behaviour as it travels along, taking into account changes in camber and road surface condition.

The work of the FOR teams around the globe is taking place alongside the rise of the connected car. It’s estimated that by 2020, one in five vehicles globally – a quarter of a billion cars – will have a wireless connection. Infotainment and nav systems will benefit immediately, but it is predicted that connectivity will expand to include vehicle-to-vehicle and vehicle-to-infrastructure – in other words, the fifth-generation roads envisioned by Collis.

“The Forever Open Road won’t happen overnight, but it will come,” says Collis. “There’s the will and, ultimately, the need to make it so.”

The road of the future - key points

1 - Porous, low-noise surface can reflect light to enhance night driving.

2 - In-built sensors monitor traffic conditions and control traffic flow, and even take control of vehicles in emergencies.

3 - In-built power system for electric vehicles.