Study Reveals Challenges in Locating Electric Vehicle Warning Signals
Researchers from Chalmers University have conducted a groundbreaking study on the effectiveness of warning signals emitted by hybrid and electric vehicles at low speeds. The study, recently published, tested the ability of participants to locate three common types of Acoustic Vehicle Alerting System (AVAS) signals.
The results showed that all tested AVAS signals were more difficult to locate than the sound of an internal combustion engine. For one particular signal type, the majority of test subjects struggled to determine the direction of the sound or identify whether they were hearing one or multiple vehicles.
Background and Methodology
Current regulations require electric and hybrid vehicles to emit warning signals when traveling below certain speeds – 20 kph in Europe, China, and Japan, and 30 kph in the United States. These signals are designed to alert pedestrians, cyclists, and other non-motorized road users to the presence of these quieter vehicles.
The Chalmers researchers conducted experiments involving 52 test subjects in a controlled acoustics laboratory. Participants were surrounded by 24 loudspeakers emitting various AVAS signals and background noise recorded from a quiet city car park. The task was to identify the direction from which the warning signals were coming as quickly as possible.
Key Findings
- The signal consisting of two tones emitted by multiple vehicles simultaneously proved to be the most challenging to locate.
- None of the test subjects could accurately locate all two-tone signals within the 10-second time limit.
- Participants easily located the sound of an internal combustion engine, attributing this to its broad frequency range and familiarity.
- The study highlighted a significant gap in current research, which has primarily focused on signal detection rather than localization.
Implications for Traffic Safety
The researchers emphasize the need for further investigation into how people react to AVAS signals in real-world traffic situations. According to Wolfgang Kropp, professor of acoustics at Chalmers, “From a traffic safety point of view, it would be desirable to find a signal that’s as effective as possible in terms of detection and localisation but which doesn’t affect people negatively.”
The study’s findings have important implications for the development of future AVAS standards, potentially influencing how electric and hybrid vehicles are designed to alert road users of their presence at low speeds.
