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This fall, a working group of the United Nations will meet to review proposed regulations that would set an international minimum sound standard for electric and hybrid electric vehicles, which would require that vehicles be equipped with a sound generating device known as an Acoustic Vehicle Alerting System (AVAS). New research from Louisiana Tech University, however, shows that the proposed sound level does not appear to add sufficient sound that would make vehicles more detectable to the average blind person than those currently on the road.
The draft regulation includes a requirement that the AVAS device emits an overall sound level of 50 dBA when the vehicle is traveling at a speed of 10 kilometers per hour (6.27 mph) and 56 dBA when traveling at 20 kilometers per hour (12.4 mph). Based on a small sample of 43 vehicles in Louisiana, the average noise level of cars ranged between 61 and 63 dBA.
“The challenge is that this group is proposing a standard and nobody has tried it in the real world,” said principal investigator Edward Bell.
The research, conducted this past April in partnership with the San Francisco Lighthouse for the Blind and Arup, an acoustics consulting firm, put the new standard to the test in a relatively quiet, flat environment. The group developed a sound file of an idling car with a standard combustion engine, played it through a speaker that had been calibrated to the level of the proposed standards.
Twenty-four participants stood listening as three vehicles, which were spaced apart, drove past them: a car with a standard internal combustion engine, a hybrid-electric car with no added sound machine, and a hybrid-electric car equipped with the AVAS system. The blind participants, who ranged in age from 18 to 58, raised their hand when they first heard the vehicle, at which time a stopwatch started until the vehicle crossed in front of them.
In the case of a standard combustion engine, participants were able to detect the vehicle approaching an average of 22 and 13 seconds away (based on the vehicles traveling at 10 kph and 20 kph, respectively). In the case of the standard, unmodified hybrid electric vehicles, participants detected them an average of 7.5 and 6.3 seconds away. When the car was equipped with the AVAS system as proposed by the United Nations working group, participants heard them 9.0 and 7.5 seconds away.
Bell summarized the findings this way.
“In short, this means that the vehicle with a combustion engine was detected significantly sooner than either the quiet car or the one with the AVAS prototype at both speeds. Furthermore, at both speeds, there is no statistical difference between the quiet car or the quiet car using the AVAS device.”
When Bell and others presented these findings to the group last month in Seoul, South Korea, no member of the panel argued with the methodology or variables used in the study. Indeed, the test was deliberately designed to allow the alert device to perform at its best.
“We used a quiet environment and smooth road surface, so you didn’t have background noise to mask the sound of the device, and essentially the device did not add any safety,” he said. “Now, when you think about putting it out on a vehicle traveling with moderate traffic or an environment with any background sound, then you will lose whatever benefit that device was supposed to convey.”
Blind people are the very ones who brought this issue to the United Nations a number of years ago, said Fredric Schroeder, the first vice president of the World Blind Union.
“We are very concerned that, based on the information that we have about how this device would work in a real world environment, this standard won’t do anything to alleviate the safety hazard of these quiet vehicles,” he said.
The research study, due to be published in the Journal of Blindness Innovation and Research in the near future, notes that there is a need for further research that would determine the minimal noise level that satisfies the public’s desire to reduce noise emissions while ensuring the safety of all pedestrians.
In the United States, the Pedestrian Safety Enhancement Act of 2010 established a process to create a minimum sound standard for quiet cars. The Department of Transportation proposed and took public comments on a set of rules last year and is scheduled to release their final rule this year, which Schroeder said is much closer to the sound level of a typical combustion engine on the road today.
The U.S. is not a party to the meeting in September, however many Western European countries, where a good number of the world’s vehicles are produced, will be present and immediately impacted by the working group’s decision.
Schroeder wants to make clear that blind people throughout the world are not interested in noisy environments.
“We’re not asking for a brass band to be put on each vehicle,” Schroeder said. “We want something that’s reasonable so that we can make a safe decision about crossing the road.”
Latest posts by Corbb O'Connor (see all)
- New research: Proposed, global standard for quiet cars won’t benefit average blind person - June 30, 2015
- Learning to Type with a Simple ‘Keystroke’ - October 28, 2014
- Unique Certification Organization Recognized with $20,000 Award - July 29, 2014
- Help Blind People Combat the Tendency to Rock Back and Forth - July 16, 2014
- Routine Class Project Changes First Grader’s Mind - June 12, 2014
