Josh Max
NY Daily News April 15, 2008
Hybrids may be a boon to the enbironment, but they pose a hazard unforeseen
by the engineers who designed them, according to a new study by the
University of California. The electric motors of hybrids are so quiet that
vision-impaired or legally blind people cannot hear them coming - and
neither can pedestrians who, increasingly, are lost in a world of cell
phones, iPods, text-messaging and other distractions.
Initial results of the tests indicate hybrids need to be up to 40% closer to
pedestrians than their gas-swilling cousins before they can be sensed, said
psychology Prof. Lawrence Rosenblum. Also in danger from the phenomen are
runners, cyclists and small children, he said.
"There is a real difference berween the audibility of hybrid vehicles and
those with traditional internal combusion engines that could have effects
on the safety of pedestrians which need to be studied," Rosenblum said.
"Our preliminary findings could mean that there is an added danger with
hybrid cars, particarly at intersections and in parking lots."
Rosenblum made recordings in a parking lot of both hybrids and gas-powered
vehicles traveling at a top speed of 5 mph. Lab subjects listened to the
results and indicated when they could hear from which direction the vehicle
drew near.
Subjects, unsurprisingly, said they heard the internal combustion engines
much sooner. Only at speeds above about 25 mph do hybrids make enough noise
to make them audible, Rosenblum said.
"This research provides evidence that hybrid cars, when operating in silent
mode, pose a substantial risk to blind people and other pedestrians. We
hope that regulators and car manufacturers will take notice of these results
and take steps to eliminate this risk, said Dr. Marc Maurer, president of
the National Federation of the Blind, a 50,000-member advocacy organization
for people who are blind or have impaired vision.
"I really do feel this is an issue for more than those who are blind,"
Rosenblum said. "We're also talking about bike riders, runners and others.
Walking around with my kids in a parking lot makes it very clear that I'm
using hearing and vision to determine where things are."
Rosenblum is continuing to study the issue, and says researchers at Stanford
University are also developing assorted different sounds to better assist
pedestrians in hearing approaching electric and hybrid vehicles.
"Everyone's aware of the issue," Rosenblum said. However, "we are not
talking about major changes to the way automobiles are designed, but about
slightly increasing their audibility when they are traveling slowly. Only a
subtle sound enhancement should be required."
