A transportation study by engineering researchers reveals that
different speed limits for cars and large trucks on rural,
interstate highways can compromise safety. “We found that speed
variation and vehicle interactions have a direct impact on
highway safety,” said Steven Johnson, professor of industrial
engineering with the Mack Blackwell Transportation Center. “Data
from previous studies and simple logic say that a higher number
of interactions among vehicles increases the chances that
accidents will occur.” Johnson reported this finding in Cost-
Benefit Evaluation of Heavy Truck-Automobile Speed Differentials
on Rural Interstate Highways, a study of speed limits and car-
versus-large-truck speed differentials on rural, interstate
highways. Sponsored by the U.S. Department of Transportation,
commercial trucking companies and private fleets, the study will
help regulatory agencies and trucking-company decision-makers
establish policies regarding speed limits and differentials for
both heavy trucks and automob