Green safety is a red-hot topic now that alternative-propulsion vehicles are part of the roadway landscape.
"Green and safe are not contradictory goals—both can be achieved and enhanced," Michael Thoeny, Global Product Line Director for Safety Electronics at Delphi Electronics and Safety, said at the Green Safety panel at the April 20-23 SAE 2009 World Congress in Detroit.
What makes a vehicle green also presents a unique set of design-for-safety considerations. "Hybrids and full-electric vehicles are generally heavier than internal-combustion engine [ICE] counterparts. Heavier vehicles will also result in greater front end stiffness, [so] vehicle occupants are exposed to relatively higher accelerations," said Priya Prasad, formerly Ford Motor Co.'s Technical Fellow in biomechanics and occupant safety and now President of Prasad Consulting LLC.
ICE vehicles typically have engines in the front. Alternative-powertrain vehicles distribute vehicle weight differently, depending on the packaging of the motor, battery pack, and controls system. "You cannot beat the law of physics. If a light car hits a heavier car, the occupant forces in that lighter car are greater," said Delphi's Thoeny.
A mix of heavy and light vehicles sharing the roadways is a given. "Until a complete fleet turnover is achieved, expect compatibility issues with the existing fleet due to mass and stiffness ratio effects," said Prasad.
Both Thoeny and Prasad said active safety systems are important in a driving environment that mixes alternative-powered vehicles with ICE-powered vehicles. "Green and safety do not have to be mutually exclusive," Prasad said, adding that the industry needs an integrated vehicle safety approach that involves infrastructure improvements, as well as enhancements in accident-avoidance and crash-protection performance.
Tomiji Sugimoto, Executive Chief Engineer at Honda R&D Co. Ltd., said drivers are a part of the safety equation since "the reality is that more than 90 percent of traffic accidents are caused by human error." Sugimoto said drivers' false sense of invincibility is dangerous.
"Accidents occur when this space shielded from the outside world creates an illusion that leads to self-centered behavior and carelessness and causes us to take action with a car that has energy that cannot be controlled by the abilities of a human being," Sugimoto said. One way to assist safety, according to Sugimoto, is having navigation and other driver-assistance tools in-vehicle so that the "driver feels good and becomes gentle whenever driving the car."