Autonomous driving on the Frankfurt Bridges is extremely safe and thus enables relaxation while driving

Today, mass transit is usually associated with stop-and-go, a view of traffic lights and other cars, and exhaust fumes. The autonomous system on the bridges makes all this disappear and allows for an environment characterized by beautiful buildings, extensive planting and a safe and gliding ride experience. A self-learning control system and additional safety mechanisms guarantee an exhilarating transportation experience.

Content: The chapter provides an overview of the comfort and safety aspects of autonomous driving on the Frankfurt Bridges

Through the central control system, each individual vehicle has access to comprehensive information about the simultaneous traffic events on the bridges. This guarantees the smooth interaction of all road users.

Low travel speeds and the protected roadway on the bridges allow the vehicle flow to operate without interference.

With modern sensor technology, hazards can be reliably detected, and intelligent control algorithms can be used to react to them quickly accordingly.

In addition, the route will also be structurally secured.

All vehicles on the Frankfurt Bridges are controlled centrally: they are all integrated into a common fleet information system

Since all vehicles are controlled by a central computer and no longer by their own steering wheel, this computer is always aware of the positions, speeds and next maneuvers of all vehicles. It also receives information about any obstacles along the route via cameras, even before the vehicles can detect them.

As a passenger you glide quietly along on the bridges

By driving with foresight, braking and acceleration can be made smooth and largely avoided.

For passengers, this makes the ride particularly pleasant: they glide along smoothly and can read, work or simply gaze dreamily out of the window.

Since all vehicles are equipped with free wifi, the driving time can be used as well as if you are chauffeured by a calmly driving professional.

Autonomous driving is one thing above all: extremely safe!

When it comes to autonomous driving, there is always one question: Is it safe? Can computers be trusted?

The answer is yes. Precisely because the system is 100 percent computer-controlled and the route, vehicles and controls were designed together, it is safer than conventional driving with the self-driven vehicles.

Analyses show time and again that the most frequent cause of accidents is human error. This can be eliminated by a computer system with multiple safeguards.

Stop speeding

All bridge vehicles can travel at a maximum speed of 30 km/h - the average is 17.8 km/h.

Nevertheless, on many routes through Frankfurt they get from A to B faster than with conventional traffic, because there is no need to stop at traffic lights, and they only stop at stations where someone wants to get on or off.

Each vehicle can thus choose the optimal routing at any time to reach its destination faster.

What's more, on the Frankfurt Bridges, the autonomously driving vehicles move in a protected "biotope," as it were.

The separation of the pedestrian path and the roadway by guardrails allows for trouble-free traffic and means more safety for people (and animals). Crossing the roadway is possible at special, secured crosswalks. There are emergency gates in the railing every few meters - but these can only be used for emergencies when passengers exit in the middle of the track.

Experts on the Topic

KIT Institut für Fahrzeugsystemtechnik - TUHH Institut für Mechatronik - Fraunhofer-Institut für Techno- und Wirtschaftsmathematik ITWM - Universität der Bundeswehr München Institut für Mechanik - BTU Cottbus-Senftenberg Lehrstuhl Technische Mechanik und Fahrzeugdynamik - TU Berlin Fachgebiet Logistik der TU Berlin

A wide range of sensors are available for autonomous vehicles for comprehensive "perception" of the environment

Another frequently asked critical question is: How well does an autonomously driving vehicle really perceive other vehicles, pedestrians or other environmental elements? What if the sensors of such a vehicle fail? A living person at least always has his or her eyes open when driving - at least one hopes so. And as long as the person driving is really looking at the road, has no visual impairment and is not too distracted, he or she will always see and possibly hear everything. But a remote-controlled vehicle?

Well, here again, autonomous driving vehicles are superior: they have not just one organ of perception or two or three, but quite a few . . . . .

Autonomously driving vehicles have more "sensory organs" than humans in order to also perceive 100% everything in time - the car therefore "sees" more

There are 8 "sensory organs" in the bridge vehicles, which use various measuring methods to detect their surroundings. In combination with extremely fast data processing, the reaction speed of a human being is significantly exceeded.

State-of-the-art sensor technology is used in the autonomous driving systems on the Frankfurt Bridges

Lidar

The environment can be scanned and mapped three-dimensionally using a LIDAR sensor. A laser source emits pulsed light waves that are reflected by objects and detected by the sensor when they return.

Induction

A conductor installed on the road is detected by a magnetic field emitted by the vehicle on the ground. This is a safety-related measure for determining position in poor visibility.

Marco Hegner – bildagentur.panthermedia.net

Odometry

Odometry can be used to determine the position and orientation of a vehicle based on data from the drive system.

Positions- und Bewegungsbestimmung

Mit Hilfe von GPS, Kamera, Radar und LiDAR kann das Fahrzeug seine absolute Position auf den HD-Karten der Brücke ermitteln. Mit diesen Informationen ist es möglich, die weitere Route zu planen, Daten über Hindernisse zu verarbeiten und vorrausschauend zu fahren.

Die umfassenden Sensordaten müssen interpretiert und übersetzt werden

Die Sensordaten erfassen die Umgebung in einer abstrakten Form. Zur Durchführung der Fahrt müssen aus diesen Daten verschiedenste Informationen berechnet werden. Beispiele hierfür sind die Bestimmung der eigenen Position in der Stadt, die Planung der Route zum Ziel, die Antizipation der Bewegung anderer Verkehrsteilnehmer, die Erkennung und Klassifizierung von Objekten sowie die Planung der nächsten Schritte.

Während der menschliche Fahrer in Bezug auf die Blickrichtung, die verfügbaren Spiegel und die Multi-Tasking-Fähigkeiten stark eingeschränkt ist, kann das autonome Fahrzeug auf die individuellen Stärken der verschiedenen Sensortypen zurück greifen und so alle diese Aufgaben simultan, schnell und in 360° Rundumsicht erfüllen – und zwar nicht nur für den aktuellen Standort, sondern auch in Bezug auf die Route, die noch vor ihm liegt.

Even if "visibility" is poor, the vehicles and their control center can still perceive everything

Via induction, GPS, and pre-programmed trajectories as well as other sensors, the vehicles always get a picture of their surroundings; even at night, in rain, fog, or ice and snow.

All measurement data is forwarded to the control system in real time. There are therefore no unforeseen driving maneuvers, as occur in regular road traffic. All driving movements are coordinated, and the system drives with foresight.

Experts on the Topic

Fraunhofer-Institut für Kognitive Systeme IKS - Deutsches Forschungszentrum für Künstliche Intelligenz (DFKI) - Fraunhofer Heinrich-Hertz-Institut (HHI)

42 Alexander Supertramp - shutterstock.com

In addition, the control center receives camera information about the entire route

Not only the vehicles, but also the track itself has sensors. Cameras are installed at the edges of the track to monitor the road at all times. If, for example, a child is spotted on the track, the autonomous vehicle approaching it knows about it before it is in sight.

With the help of the cameras' viewing angles, the camera network along the route was selected to be so close-meshed that no danger remains undetected. Around 35 cameras are needed per kilometer of track for each lane. The data processing of the camera images takes place in the so-called supply centers along the route.

In conventional road traffic, the main problem for autonomous vehicles is how to respond to random human and animal behavior

The vehicle, of course, cannot assess the condition and spontaneity of a passerby - it simply stops when anything, human or animal or otherwise, even approaches it.

The main problem with autonomous driving vehicles is not that they are more likely to run over something, but quite the opposite: that they stop immediately upon sighting the smallest potential obstacle.

On the bridges, this is largely avoided by the specially protected driving sections: people only have free access to the roadway at the stations and thus only there the possibility of bringing the vehicles to a standstill by erratic behavior.

On the Frankfurt Bridges, the vehicles have the advantage that they travel on proprietary routes shielded from other road users and thus act particularly safely

As soon as autonomous driving is transferred to city streets, the routes there will have to be "secured" as well: The slimmest option for this is guardrails

Not only boring standard railings should be used, but preferably pretty appealing designs should be brought to bear: Because if you imagine these railings on all the streets of a city, then a pleasant appearance is extremely important. There can be crossings for pedestrians every 10 to 20 meters, but the rest of the roadway must be demarcated, because autonomous driving cannot be implemented as an overall traffic system without safeguarding the road.

Fahren im Gruenen - Stiftung Altes Neuland Frankfurt / GNU

Tuermchenplatz - Stiftung Altes Neuland Frankfurt / GNU

With plain railings, planters can serve as a softener

Plants in planters along the roadside should be ground based and have water storage layers in the clay pots to keep them well maintained without a lot of manpower.

In terms of design, you can get ideas for planter boundaries to the roadway from the countless enclosures that restaurants make for their outdoor areas facing roads.

Autonomous driving systems still need to be further developed in order to optimize them logistically. This will require a larger complex traffic network, such as that represented by the Frankfurt Bridges

Once such systems are so well developed that they can offer people individualized transportation services instead of individual car ownership, studies show that the number of vehicles on the road will be reduced by more than 80 percent

If there is more space at the roadside because autonomous driving systems require fewer vehicles and thus fewer parking spaces, but at the same time all lanes have to be secured, then former parking spaces can also be planted with hedges or low shrubs at the roadside as a safeguard.

Parkplaetze_in_der_Zukunft - Stiftung Altes Neuland Frankfurt / GNU

Heidetraum Noack Rosen - www.gartenpraxis.de

With even more space along the streets, so-called "parklets" can also be created

The reduction of cars through centrally controlled autonomous vehicles leads to more space for green in our inner cities and also creates new experience spaces: the "Parklets". These can be designed in completely different ways. And since engines will be largely emission-free and quiet, sitting by the road will then also be fun.

Autonomous vehicles react significantly faster than humans to unforeseen events in traffic or in their environment

If something unforeseen does happen, the system reacts in fractions of a second, faster than a human could. At the same time, the driving behavior of all other vehicles is automatically adjusted. They slow down, choose a different route or pull into a lay-by to make way for any emergency vehicles. Unexpected emergency braking and evasive maneuvers are therefore (virtually) non-existent.

So far, about one third of microplastics in Germany comes from tire wear: Since autonomously driving vehicles have significantly fewer and slower braking processes, they also release significantly less microplastics into the environment

So far, there are only routes with autonomously driving vehicles that drive a certain way back and forth on their own lane. However, in order to be able to convert future urban traffic completely to autonomously driving, centrally controlled vehicles, large test routes are needed, such as the Frankfurt bridges. Only through live application can such a highly complex system be developed.

But the effort is worthwhile, especially with regard to nature and future generations: More and more microplastics are being released into nature and from there enter our organisms. Usually, we think of plastic in the sea as the main source of pollution. But in Germany, one third of the microplastic that enters the environment comes from tire abrasion. With the help of central systems for brake-reducing control of all vehicles, at least this largest source of microplastics in Germany can be significantly reduced.

On the bridges, railings and masonry provide additional safety for people and animals

It may be able to perceive a pedestrian eight times over, but can it judge whether the pedestrian is brave enough to run across the street in front of it?

Therefore, on one side the roadways are separated from the sidewalks by decorative railings. On the other side of the lanes are natural meadows, to which only a small wall protects against small animals. The vehicles thus drive completely undisturbed by people and animals.

If someone does make it onto the roadway, the autonomous vehicles are equipped with safety sensors and apply the brakes.

Another safety factor: Vehicles cannot deviate from the lane and are stabilized by the roadway shape

The lowering and shape of the lanes ensure that vehicles do not stray from the path.

The vehicles, which only travel at a maximum speed of 30 kilometers per hour, are thus prevented from going off the tracks under their own power thanks to a 35-cm-deep lowering of the track.In addition, the road surface is concave in shape, which automatically stabilizes the vehicles in the middle.

Furthermore, the lanes are separated from the sidewalks in many cases by a 10-centimeter-high plinth to which a decorative railing is attached. Thus, vehicles cannot drive onto the sidewalk, nor can pedestrians unintentionally enter the roadway.

As a further safeguard, bollards are installed at all Curves of the bridge route provided

At curves, bollards about one meter high are additionally embedded in concrete to prevent passengers from jumping out of the troughs. however, these bollards have more of a psychological function: they show passengers that everything is being done to ensure their safety.

Experts on the Topic

BTU Cottbus-Senftenberg Lehrstuhl Technische Mechanik und Fahrzeugdynamik - Institute of Automotive Engineering (FZD) - Hochschule München Fakultät für Maschinenbau, Fahrzeugtechnik, Flugzeugtechnik - KIT Institut für Mess- und Regelungstechnik (MRT)

As a further safeguard, bollards are installed at all Curves of the bridge route provided

And in the first years there are still bus and train attendants - so that everyone feels well looked after at all times

Autonomous driving is unusual. A bus without a driver, a streetcar without a female driver? Currently, this would be rather frightening for most people. That's why bus and streetcar attendants will always ride along on the Frankfurt bridges in the first few years. They serve as contact persons; answer questions, show how to use the app, and help with uncertainties and anything else that comes up. For seniors in particular, it is important to have someone they can turn to with their questions.

The roadway on the Frankfurt Bridges always remains in perfect, safe condition

The protected character of the traffic routes on the bridges means that the roadways are always in good condition.

There are no environmental influences such as the deformation of the pavement of the roadways by tree roots, since no trees or only plants suitable for the bridge structure are planted on the bridges.

Since there is a geothermally heated system under the roadways and frost thus cannot damage the road surface either, the roadway remains level and the ride with the vehicles on the bridges almost vibration-free and extremely quiet.

The roadway on the Frankfurt Bridges is level, collects irrigation water and remains frost-free and safe to drive on even in winter

The roadway on the Frankfurt Bridges has a rainwater collection system, which provides additional irrigation water for the plants on and next to the bridges.

In addition, a thin metal strip is integrated into the roadway with the wastewater grid strip, which is used by the autonomous system for navigation.

Through a sophisticated network of water pipes running underneath the roadway, excess geothermal energy is used in winter to keep the road frost-free at all times.

Safety and comfort go hand in hand: the central control system optimally adapts the speed of the vehicles to the course of the road for every meter traveled - thus reducing the risk of accidents to almost zero and increasing comfort, as passengers do not get dizzy on curves

On the Frankfurt Bridges, the central system optimizes the speed of the vehicles in the curves so that the lateral acceleration is always below 1.5 m/s2. This is possible without any special effort because the central control system knows the exact nature of all curves. Acceleration (to a maximum of 30km per hour) only takes place on straight stretches.

This ensures maximum safety, but at the same time increases comfort: when driving a car on curvy roads, some people quickly become nauseous. This happens because the driver of the vehicle enters the curve at high speed or accelerates when leaving the curve. The occupants thereby experience a high, so-called lateral acceleration.

Experience shows that passengers in conventional local passenger transport are exposed to maximum lateral accelerations of approx. 2.0 - to 2.5 m/s2 . As the vehicles on the Frankfurt bridges reach their destination comparatively quickly when optimally controlled, high speeds or accelerations on curves are unnecessary.

In order to exploit all the advantages of possible steering concepts for the best possible and space-saving routing on the Frankfurt Bridges, various steering concepts were compared

Usually, vehicles are steered by steering the front axle. However, it is also possible to steer the rear axle as well in order to negotiate tighter and narrower curves.

For maximum driving comfort and ease of steering, vehicles use hybrid steering, which has a steering ratio of 0.7 between the front and rear axles. The influences of the steering angle on the inside radius of the curve and the road width are shown graphically for the individual steering concepts.

The carriageways on the Frankfurt bridges are designed from the outset with a view to maximum safety and the best possible comfort: For example, the dimensions of the towing curve of the largest vehicle were calculated and it was ensured that each curve could be navigated comfortably

For a large vehicle to be able to drive around a curve, it must not be too narrow or too tight. Therefore, the towing curves of the largest vehicles on the Frankfurt bridges were precisely determined using geometric relationships. Not only the wheelbase but also the front and rear overhangs are relevant here. The data shown are valid for the Neoplan NH 6/7 model, which has the largest vehicle dimensions.

The route on the Frankfurt Bridges was planned according to the towing curves of the largest vehicles: Safety, driving comfort and smooth - i.e. time-saving - traffic are thus ensured

When planning the route, the radii and widths of the curves were created digitally and compared with the calculation results, ensuring that the route is suitable for all vehicles.

Conclusion: The highest level of comfort for autonomous driving will be possible on the bridges - as an attractive alternative to private transport.

Guardrails facing the sidewalks and automated pedestrian crosswalks keep the travel lanes on the bridges free of outside influences.

These protected, exclusive driving routes make it possible to solve the traditional problems of autonomous traffic systems: No vehicle is interfered with or brought to a halt by the arbitrary actions of humans or animals. In addition, all vehicles act exclusively under central computer control, which means that no road user can interfere and impair the optimized system.

High comfort, exceptional safety and speedy transport performance are the result.