22 MOMENTUM • VIRGINIA TECH MECHANICAL ENGINEERING
INCREASING SAFETY FOR ELECTRIC CARS AND PEDESTRIANS
An interdisciplinary research group at Virginia Tech is using an award of $ 550,000 to create a virtual environment to test safety measures for the interaction between electric vehicles ( EVs ) and pedestrians . The award is an 18-month project funded by the Safety through Disruption ( Safe-D ) University Transportation Center .
EVs brought a significant change to the automotive world when Toyota started mass production of the Prius hybrid in 1997 . The Prius engine and many like it introduced a combination of both gas and electric power . This gave the horsepower of gasoline when it was needed , engaging all-electric mode at other times to conserve fuel and reduce emissions .
All-electric mode has another notable difference when compared to an internal combustion engine : noise . While a gas engine announces itself from a distance , electric engines make almost no sound , and are easily drowned out by other ambient noise . Car noises are actually a critical safety measure , making the presence of a vehicle known when approaching pedestrian crosswalks and other areas where foot traffic might intersect with automobiles . This is particularly important for pedestrians with a visual impairment .
To solve this potential safety problem , manufacturers have been developing an acoustic vehicle alerting system ( AVAS ) for use in new electric and hybrid electric vehicles . These systems make a continuous noise when the car is moving slowly , its loudness between that of a normal conversation and a garbage disposal .
Legislation has been moving forward to require these safety measures on EVs , with the most prominent examples coming from the United States and the United Nations Economic Commission for Europe . While the law creates a range of decibel levels , there are many approaches for the type of sound that might best be put into use . Early choices included such options as spaceships and choirs .
The Virginia Tech project will bring legislation together with practical implementation and testing . Taking lead on the project is