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New communication signals help road users understand automated heavy vehicles

23 May 2023, 12:54

To effectively communicate with each other in traffic, we rely today on a range of signals – such as traffic lights, turn indicators, and eye contact. With the advent of automated vehicles, the communication landscape in traffic is transforming. How will automated vehicles integrate into traffic while ensuring understanding and trust among other road users, including pedestrians and human drivers? A research project shows that new communication signals could be vital in various traffic situations and that these signals need to be standardized, cost-efficient, and compatible with other features on vehicles.

The research project “External Interaction Principles for Creating Trust in Heavy Automated Vehicles” was a collaborative effort between Scania CV AB, RISE Research Institutes of Sweden, and Halmstad University. The project investigated new communication signals from automated trucks and buses and concluded that such signals could aid other road users in understanding intentions and actions of these vehicles, fostering trust and ensuring safe interactions.

Key findings from the research project:

  • Road users anticipate that future automated trucks and buses will communicate key information to surrounding traffic through both their movements and new external human-machine interfaces (eHMI).
  • Signals indicating whether a truck or bus is operating in automated or manual mode could help other road users distinguish between different driving behaviors of human drivers and automated systems, thus avoiding potential mismatches and enhancing safety.
  • Signals conveying the intent of automated trucks or buses could provide clearer and earlier indications of planned actions to surrounding traffic, potentially replacing the information currently obtained from human drivers during negotiation situations.

“The research findings demonstrate that effective communication is essential for the successful integration of automated heavy vehicles into traffic,” stated Daban Rizgary, Senior Researcher at RISE Research Institutes of Sweden. “By employing innovative communication signals, we can bridge the gap between human and automated driving systems, fostering trust and ensuring a harmonious coexistence on the roads.”

image received via email

Visualization by Scania.

Supported by funding from the Swedish Strategic Vehicle Research and Innovation Programme (FFI), this project was initiated to address the current knowledge gap within the research community and industry regarding interactions between automated heavy vehicles and other road users. Through extensive evaluations involving over 80 participants, different eHMIs in the form of abstract lights, icons, and text were designed and assessed.

Results indicate that road users anticipate the use of novel signals from future automated trucks and buses. “Given that automated vehicles are quite new to road users, uncertainty may occur in their communication, and it is important to make them understand each other,” commented Yanqing Zhang, Human Factors Specialist at Scania. “As traffic is a social phenomenon, enabling our future trucks and buses to communicate in a manner similar to human road users can enhance overall trust and acceptance of these vehicles. Being a vehicle manufacturer with safety and efficiency as core values, it is important for us at Scania that people feel safe when encountering our future products on the road.”

According to the findings, other road users could benefit from knowing whether they are encountering a vehicle operated by an automated driving system. Signals conveying the vehicle’s intent through eHMI could enhance perceived safety and understanding. This emphasizes that eHMI can clarify and complement intention signals conveyed through the vehicle’s movement, placement on the road, and sound.

One distinguishing aspect of this project is its exploration of novel communication signals in both urban and highway contexts as well as in confined spaces such as warehouses. The research team embraced the principle of “less is more” and ensured that both the information and its design were minimalistic, without instructing other road users on how to react. For scalability to a larger vehicle fleet, these eHMI must be both cost-efficient and compatible with other features on vehicles.

Daban Rizgary further emphasized the need for standardized signals, stating, “Simple light signals could be sufficient, but standardization is crucial to ensure their effectiveness. We actively participate in ongoing standardization activities to drive progress in this field.”

This project addressed critical aspects of future traffic interactions and provided initial design recommendations for new eHMI that are valuable to the industry. “However, we acknowledge the need for further research,” noted Yanqing Zhang from Scania. “Our studies were conducted in controlled conditions, such as test tracks, driving simulators, and videos. To generalize our results, it is essential to conduct more extensive studies that encompass a larger population and capture the complexity of real-world traffic.”

Given that this research field is in its infancy, competence development is also necessary. “It is worth mentioning that a licentiate thesis has been produced as part of the project and will be unveiled by Victor Fabricius on May 24th, 2023, at Halmstad University.”, emphasized Pontus Wärnestål, Deputy Professor, Halmstad University. Furthermore, the findings will be shared at a seminar titled "External HMIs - A comprehensive dialogue on communication and interaction with forthcoming vehicles," scheduled for May 29th, 2023, at the SAFER Vehicle and Traffic Safety Center.

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Press contact:

Niklas Jälevik, Head of media relations, RISE


Facts about the project and the partners:

The project "External Interaction Principles for Trust and Acceptance of Heavy Autonomous Vehicles" has been partially financed by Vehicle Strategic Research and Innovation (FFI - Diary number: 2019-05901) and is associated with the SAFER Vehicle and Traffic Safety Center. The project has included two master’s theses and a licentiate thesis. The project lasted approximately 2.5 years.

Scania is a world-leading manufacturer of sustainable transport solutions, including trucks and buses used for heavy transport. Scania has approximately 52,100 employees in 100 countries, where the main production takes place in Europe, while research work takes place mainly in Sweden but also Brazil and India. Scania is part of TRATON GROUP together with MAN, Navistar and Volkswagen Caminhões e Ônibus.

RISE is a non-profit research institute with a focus on sustainable mobility. The goal is to support Swedish industry in achieving sustainable development and growth. RISE has established itself as one of the major research players within automated vehicles in Sweden. RISE is involved in research projects both nationally and internationally, where one of the subjects being researched is precisely interaction between automated vehicles and other road users.

Halmstad University has extensive experience in research in transport and vehicle automation. Research activities done include Smart Electronic Systems, System of Cyber Physical Systems, Awareness, and Digital Service Innovation.