As the introduction of automated vehicles becomes feasible, even in urban areas, it is necessary to investigate their impacts on traffic safety and efficiency. This is particularly true during the early stages of market introduction, where automated vehicles of all SAE levels, connected vehicles (able to communicate via V2X), and conventional vehicles share the same roads with varying penetration rates.
There will be areas and situations on the roads where high automation can be granted, and others where it is not allowed or not possible due to missing sensor inputs, high complexity situations, etc. At the border of such areas many automated vehicles will change their level of automation. We refer to these areas as “Transition Areas”. It is very likely that Transition Areas will have a negative impact on traffic safety and efficiency, since transitions of control may fail or lead to non-optimal behavior.
TransAID develops and demonstrates traffic management procedures and protocols to enable smooth coexistence of automated, connected, and conventional vehicles, especially at Transition Areas. A hierarchical approach is followed where control actions are implemented at different layers including centralized traffic management, infrastructure, and vehicles.
To achieve this, modelling of the existing and upcoming automation functionalities and driver behavior has been done as a first step, including modelling of transitions of control as well as automated lane changes and speed/distance keeping. This is a mandatory step to get insights not only into current situations, but also to predict the future impact. Therefore, the models have been used to perform simulations in different shares and in a set of 10 use cases. The simulations proved that there is a negative impact on safety, efficiency and CO2 emissions caused by transitions of control and minimum risk maneuvers. By following the hierarchical approach, infrastructure-assisted management solutions have been investigated and simulated advising connected, automated, and conventional vehicles at Transition Areas, taking into account traffic safety and efficiency metrics. These solutions aimed at the prevention of transitions of control and minimum risk maneuvers by providing speed, distance, lane or path information. Also in focus was the distribution of transitions of control along the road. In case a transition of control is unavoidable, the developed solution supported connected automated vehicles to find a safe spot for performing a minimum risk maneuver.
As cooperation between infrastructure and connected/automated vehicles is a key requirement, V2X communication protocols using ITS-G5 have been developed, including collective perception (CPM) and Maneuver Coordination (MCM). Measures to detect and inform conventional vehicles are also addressed.
The most promising solutions have been implemented as real world prototypes and demonstrated under real world conditions, on test tracks and on a highway in the Netherlands. The implementation included road side components (sensors, including object detection and tracking, variable message signs) as well as vehicle components (automation function, HMI) and the communication. Feasibility assessments have been performed using these prototypes, and their results have been used to further enhance the traffic management solutions.
Finally, guidelines for advanced infrastructure-assisted driving have been formulated. These guidelines also include a roadmap defining activities and needed upgrades of road infrastructure in the upcoming fifteen years in order to guarantee a smooth coexistence of conventional, connected, and automated vehicles.
