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Road Infrastructure ready for mixed vehicle traffic flows

Periodic Reporting for period 2 - INFRAMIX (Road Infrastructure ready for mixed vehicle traffic flows)

Reporting period: 2018-12-01 to 2020-05-31

The INFRAMIX project focused on the transition period, where both conventional and automated vehicles will share the roads. Particularly in the beginning of this transition period, there is the risk of negative effects on road efficiency and safety if no measures are taken. Road infrastructure will play a major role in managing this transition period to make heterogeneous traffic faster, smoother, safer, acceptable and socially beneficial for all traffic participants.

The main objective of the INFRAMIX project was to design, upgrade, adapt and test both physical and digital elements of the road infrastructure to achieve a “hybrid” road infrastructure for future automated transport systems.

In order to achieve this target, INFRAMIX has:
• Developed a co-simulation environment;
• Designed and implemented novel traffic estimation, monitoring and control strategies;
• Developed hybrid testing systems;
• Evaluated traffic efficiency, safety and user’s appreciation;
• Created a Road Infrastructure Classification Scheme.

INFRAMIX investigated three key traffic scenario:
• Dynamic lane assignment: The assignment of a dedicated lane to automated traffic to reduce safety concerns about the penetration of the automated vehicles in conventional traffic.
• Roadworks zones as major safety hotspots requiring efficient coordination of mixed traffic flows.
• Bottlenecks: real-time control of mixed traffic to avoid traffic flow degradation.

Two test sites have been selected:
• The Spanish test site on the Mediterranean Corridor between Barcelona and the French border. The specific highway segment is over 20km of four-lane carriageway, including ITS equipment.
• The Austrian Test Site includes about 20 km of A2 highway between Laßnitzhöhe and the City of Graz equipped with latest ITS equipment.

The evaluation of the INFRAMIX solutions has shown that physical and digital infrastructure support will significantly help to improve traffic efficiency and safety.
The project has prepared road infrastructure for mixed traffic of conventional, connected and automated vehicles.

Within the scope of the INFRAMIX project the next generation of these C-ITS services were successfully tested in Europe for the first time. INFRAMIX implemented the ITS-G5 short range technology according to the latest C-ITS communication standards, working closely with standardization working groups. INFRAMIX also implemented a cellular connection(4G) from infrastructure via service provider to the vehicles and hence realised a hybrid communication system.
INFRAMIX traffic scenarios were tested via simulation and on real stretches of advanced highways and via a combination of virtual and real world testing. Furthermore, a new traffic sign was proposed for indicating the lane dedicated to automated vehicles. Advanced simulation tools were implemented, for an extensive evaluation of INFRAMIX developments. Innovative traffic estimation and traffic control strategies were developed and applied. The evaluation of the INFRAMIX solutions has significantly shown that physical and digital infrastructure support will help improve traffic efficiency and safety. The results showed that
- speed recommendations had positive impact in terms of safety
- time gap adaptions can enhance traffic efficiency by more than 50%
- travel time delay at bottlenecks could decrease by more than 14%, even with low penetration rate of connected and automated vehicles.

An infrastructure classification scheme (ISAD) has been developed, which can be a guide for road operators and authorities to target investments on what is needed for supporting higher levels of AD functions.
Traffic estimation algorithms
The use of traffic estimators allows the reduction of the total number of spot sensors, and consequently the cost for traffic monitoring. The evaluation results show, that the developed tool for a cross-lane case has reached maturity allowing immediate exploitation.
Traffic control strategies
Various control strategies were developed and tested with respect to the project scenarios and use cases. Three controllers were tested within INFRAMIX: an Acceleration Controller (ACC) for adjusting the desired time-gap to the leading vehicle, a mainstream traffic flow controller via Variable Speed Limits (VSL), and a controller for Lane-Change Advice (LCA) to connected vehicles at bottlenecks. Very promising evaluation results could be achieved.

Infrastructure classification scheme / ISAD classes
Similar to the SAE levels for the taxonomy of AVs, the ISAD classes classifying the road infrastructure based on its capabilities to support different levels of AVs have been developed. ISAD classes could support to bridge gaps in AD functions which are limited by the ODD. They will guide public administrations and road operators to target investments on what is needed for supporting higher levels of AD functions and regulators to define the new regulatory frame of Intelligent Transport.

Co-simulation environment
Coupling microscopic (VSimRTI) and sub-microscopic (ICOS) simulation environments was a key innovation of INFRAMIX combining the advantages of both approaches. With microscopic traffic modelling, some cases and traffic situations focus mainly on the physical and digital capabilities of the infrastructure. On the other hand, sub-microscopic models allow to test vehicle dynamics and behaviours that support the evaluation of user perception and safety in a more realistic way, but are more complex and computationally demanding. The co-simulation framework could be used in future research.

C-ITS messages enhancements
Enhanced data profiles of ITS-G5 (IVI) messages were used and a version of the IVI standard (ISO 19321), enhanced with a new message-container, was applied for the first time in a real environment.

Hybrid Communication
Both (C-ITS G5 and Cellular) communication technologies were used. The INFRAMIX Management Center (IMC) has been established and applied as a core element for the dissemination process. The communication flow from the IMC to the Cellular Service Provider as well as to the RSU has been performed in real-time. Additionally, a communication between the IMC and the Traffic Management Center has been applied in the Spanish test site centrally activate digital road signs.

New visual signs
The coexistence of automated, conventional and connected will require new signalling. Based on the visual requirements of the project scenarios, INFRAMIX implemented new visual signs (DLA, end of DLA) or various combinations of existing signs (Speed Advice, Lane Change, Roadworks, Speed Limit, Time Gap), receiving great user acceptance.

Hybrid testing
A new hybrid research methodology on proving grounds was an innovation provided by INFRAMIX. Advanced driver assistance functions on a real vehicle platform in virtual mixed-traffic scenarios, new developments of connected and automated driving and the effect of real-world C-ITS messages in virtually defined scenarios were tested. The results were analysed using a combination of real-vehicle measurements and simulation data. The main overall observation is that the speed recommendation for the connected and automated vehicle traffic have positive implications in terms of safety, whereas the lane change recommendations usually lead to underutilization of traffic flow efficiency and creates risky traffic situations.