Asphalt Gold.

30 million kilometers of precision.

Road construction hides a complexity which is not apparent at first sight. To ensure that the road is kept away from the soil, this first needs to be compacted. Before the first layer can be applied, the ground often needs to be stabilized with the addition of asphalt, chalk or cement. Then comes a gravel or ballast layer to protect the road against frost. This loose substrate is followed by a bonded layer which defines the actual look of the road: Asphalt, paving or concrete.
The highway is the jewel in the crown of road construction as an art form; it is its highest technical achievement. For only one single kilometer of highway, countless HGV loads speed along every minute to huge machines with names like 'slipform paver', mighty heavy factories on wheels. To do this, these giants have to be steered with precision using sensitive sensors. The connection between two roads is allowed only a tolerance of 4 millimeters.

Streets without age.

In addition to asphalt, which makes up the largest proportion of Germany’s road surfaces, there is an increasing use of concrete as a construction material. While it is 20-30% more expensive than its black counterpart, concrete is more resilient and more resistant to heat. Well over double the service life of up to half a century is achieved, and, according to researchers at the University of Delf, concrete roads of the future could even be self-repairing. The team mixed bacteria into the concrete which can lie dormant in the road surface for up to 200 years. If cracks form, the moisture reaches the microbes and they produce chalk. This seals the road once again.

The digital road.

According to the Federal Office for Road Construction, movement and pressure sensors are to be integrated into motorways to measure, for example, traffic volume and wear. Currently, the number of vehicles or the state of the cracks between the concrete slabs is still determined using visual inspection. Smart roads, in contrast, will report if they are overloaded or if a repair is required. A detected pothole or a traffic jam can also be transmitted to networked vehicles. Road builders are able to capture the road requirements much more precisely. To supply the various sensors, the Federal Office is also planning to integrate piezo elements into the road surface to produce electricity from the pressure of the vehicles.

Signs on the asphalt.

So far, it has been predominantly traffic flow which has been recorded but not guided by sensors in the road surface. For this, classic analog road surface markings have been relied upon. But in the digital age, it is even possible to make the paint a little bit more intelligent – this was thought up by a Danish design studio and they developed the road markings of the future. The paints are regulated by the weather and time of day. At night, they start to glow, in frosty conditions, temperature-sensitive markings in the form of snowflakes appear. Currently, road markings are mainly for separating the lanes. Sometimes, they are aided by electronic signs which assign the lanes to one of the two road sides depending on traffic volume. But, in the age of autonomous automobility, do we even need lane markings anymore?

Forms a corridor.

A car which automatically keeps its distance and communicates with other vehicles around it could also manage without road markings. The vehicles would decide for themselves at lightning speeds whether they should assign their own lane to the oncoming traffic or even open up a completely new one. This kind of traffic would not only be more dynamic but also safer. Emergency vehicle access lanes could be formed much more quickly if the autonomous cars have already been warned by the ambulance or police car several minutes ahead of time. Depending on the traffic situation, a two-lane motorway could suddenly be converted to three lanes. The sensors in the road would be immediately involved in the thought processes and allow the changed traffic situation to be incorporated into the route calculation.

Always on the go.

Let's take this one step further. Why do we need signs if, for example, the speed limits can be flexibly adapted to the traffic situation? The perfect speed for a specific time can be left to the swarm intelligence of the autonomous fleet of vehicles. There will also be no need to provide warnings for sharp bends in the road. They are already marked in the navigation system or detected by camera systems well in advance; weather or road conditions are detected by the tires. Even traffic lights can be dispensed with completely. According to concepts from MIT and studies by the University of Clemson, it is possible to reduce the number of junctions for waiting cars by 99% using driverless control. The next step to perfection? Light traffic instead of traffic lights!

The road of the future will reduce the number of parking spaces. Of course only the markings are referred to here. In future, sensors, which are applied like tattoos on the asphalt, will report the available spaces.

Since the length of the car can be included in this, the number of parking spaces will be dynamic. BMW and INRIX are currently working on a realtime analysis of movement data for cars entering and reversing out of parking spaces via GPS. This will derive the statistical probability of where free spaces are most likely to be. The roads will soon be able to take over this task from the satellites.

Even the last compulsory stop – refueling – could be dispensed with by using electric cars. First of all, a road could also produce electricity – if, for example, solar panels are integrated into the surface. This is no pipe dream. Cycle lanes in the Netherlands and roads in France and the USA are already providing emission-free electricity. It could then be fed directly into the cars. Induction coils integrated into the road surface would make charging stations increasingly superfluous. In Seoul, already a pioneer when it comes to smart cities, coils like this have already been embedded into the asphalt so that buses can charge wirelessly at bus stops.

Free train.

A road full of autonomous cars, no lane markings, no signs, no traffic lights, no filling stations. Sounds really extraordinary, but it’s quite possible. The more fluid the traffic, the safer and faster everyone will arrive at their destinations. Regarding speed: Wouldn’t a car be faster if the road itself sped it up? This kind of idea led to a great deal of testing of magnetic levitation trains. The German Transrapid trials may have come to an end, but perhaps the cars of the distant future will actually be speeding silently across countless branches of magnetic fields, powered by the sun. As zeppelins were still flying through the air, early 20th century town planners imagined streets on many levels which would tower up to the heavens. Will their dreams one day become a reality?

Authors: Christian Geiss and Leo Burkhardt