IT WAS SUMMER 2000, AND LAURA SCHEWEL
was driving to her internship position in Richmond, Virgina. As
she passed through a notoriously dangerous intersection, a
Class-D truck barreled into the side of her ’98 Honda Accord.
Luckily, she walked away from the crash. A full year later,
after many hours of physical therapy, Schewel’s back injury had
fully healed, but getting behind the wheel again remained a
nerve-wracking ordeal.
Thankfully, time heals on many levels and Schewel’s
experience on that early August morning cultivated a professional
interest in automotive safety and design. Back then there was no
way to imagine that only eight years later she’d be crashing two
vehicles together hundreds and hundreds of times—albeit
virtually—just to see what would happen to the people inside.
When Schewel joined RMI in 2006, her first assignment was
to update Winning the Oil Endgame, RMI’s 2004 roadmap for
getting the United States off oil. But when she had the chance to
lead a project aimed at making vehicles as safe as they can possibly
be, she jumped at it. Simply put, she was asked to look into the
notion that lightweight vehicles can be just as safe as regular
vehicles. By studying the dummies and vehicles that she
repeatedly crashes in computer simulations, and examining the
physics behind those collisions, Laura now has the opportunity to
fully understand the forces she previously experienced firsthand.
“There’s a lot of compelling anecdotal evidence that light
cars can be as safe as regular cars,”
she says, “but there was no academic
or statistical base. As I catalogued
the studies that had been done, I
realized there was a really significant
gap in the literature.”
The “gap” she mentions was
simply the fact that while there were
studies that described what might
happen to people in a car that was a
few pounds lighter, there was
nothing describing what would
happen with a car that had gone on
a real diet—and lost, say, 40 to 50
percent of its mass.
“In every major study there’d be this little footnote that said
while lighter is not necessarily more dangerous, we don’t want
to be held to that statement up to more than 100–200 pounds,”
she says. “Those little footnotes were a problem for us.”
So, Laura wrote up “a little paper” about the many ways
vehicles can be safer for the planet and for both drivers and other
road users and presented it at a Society of Automotive Engineers
conference where it was well received. With that success, she
subsequently wrote a blog post for Yahoo! Green about the subject.
Yahoo!’s editors liked the piece so much they moved it to
their homepage, where it was viewed
more than 300,000 times.
“All of a sudden the site traffic
for rmi.org went crazy, and people
were sending me death threats via
outreach,” she recalls. “I thought,
wow, this is really a hot topic. We
should pay a bit more attention to it.”
About the same time—as luck
would have it—Schewel had crafted
a proposal centered on exploring the
literature gap. A flurry of emails
went around RMI, the proposal was
submitted and, just a week later, the
William and Flora Hewlett Foundation committed to fund
the project.
Today, RMI’s MOVE Team is deep into researching whether
lightweight cars can be just as safe as heavy cars.
Model Dummies
The research involves creating
computer models to simulate
crashes of lightweight vehicles and
popular on-the-road vehicles of
about the same size. MOVE Team
Analyst Mike Simpson is in charge
of the modeling and is working
with a subcontractor who will
generate 500 virtual crashes in real-
world configurations.
RMI Analyst Mike Simpson reviews simulation data.
Most people, says Simpson,
assume that in a collision a heavier car will fare better than a
lighter one.
“The computer models are based on Newton’s Laws but you
don’t have a solid single particle the way most people expect,”
he says. “You actually have multiple components that all react
differently depending on their orientation, the material they’re
made of, their mass, the components around them they
react with, and other considerations. And there are so
many different materials in a car that it becomes a pretty
complicated problem pretty quickly.”
Specifically, the computer doing the modeling divides the
cars into tiny tetrahedrons (pyramid-shaped particles) that
represent parts of the car. Millions of the tetrahedrons might
represent the bumper, for example. Tens of thousands might
make up a door handle. The tetrahedrons are then assigned
values for various characteristics of that component (density,
material characteristics, deformation properties, etc.).
“The bumper, for instance, is a single piece of metal or
plastic,” Simpson explains. “But you don’t analyze it as a
single solid piece of plastic or metal.”
The computer will then pull together what happens to the
millions of tetrahedrons and generate images and animations
of how the vehicle deforms, where the forces are greatest, and,
ultimately, what happens to the people inside.
The larger the number of particles studied, the clearer
the picture becomes of what happens—“higher resolution,”
Simpson calls it.
Once the testing is complete, MOVE researchers will write
a technical paper on their findings and publish it on a dedicated
Web site. In addition to this crash testing, Schewel will design
a market survey to query vehicle buyers on their attitude toward
light vehicles.
The Target Audience
The MOVE Team has several specific audiences targeted for
this research. First are vehicle buyers themselves, who, according
to MOVE Team research thus far, are overwhelmingly women
in their 20s, 30s, and 40s.
The second audience—perhaps the most important one—
consists of insurance providers. Some members of the insurance
industry associate lightweight cars with danger. That’s because they're accustomed to steel cars. And
steel cars that are lighter have, by
definition, less steel in them, which
makes them more dangerous.
Anything that’s new to
insurance companies is going to
be an inherent risk,” says Simpson.
“That’s just how insurance
companies operate. And insurance
companies know steel vehicles
because that’s all we have.”
Besides the obvious
greenhouse-gas emissions and fuel
savings-related benefits of lightweight cars, Schewel is quick to
point out that there are huge benefits to the people who might
be hit by lightweight cars: pedestrians, cyclists, and drivers of
other vehicles. That means that the government will become
another key audience.
“All the indications are that the benefits to other road users are
going to outweigh benefits to the car drivers themselves,” she
notes. “And it is absolutely in the insurance industry and
government’s interest to promote those societal benefits. In
Europe they’re really focused on pedestrian safety and ‘other-car’
safety but that wave of regulations hasn’t hit the U.S. as hard yet.”
One of the big challenges with lightweighting cars will be
aligning individual consumer interest with societal goals. There
are ways to do that, Schewel says, but for now, she’s just glad
that the effects of lightweighting on carbon emissions and safety
look extremely positive.
“Car crashes are the second-leading cause of death among
young people between five and 29 years old, worldwide,” Schewel
adds. “So it’s an extraordinary example of multiple solutions for
a single expenditure, if you can simultaneously bring down these
two scourges on society: global warming and traffic deaths.”
