Interstate 84, which runs through Danbury, is scheduled to be widened to a six-lane highway at all points between Danbury and Waterbury. State officials say they hope the widening will not only benefit drivers regularly on the route but also entice some cars from the more crowded Interstate 95, which is roughly parallel to it. Heavier trucks are unlikely to use Interstate 84 more often, however, because the route is much hillier than I-95 according to a state Department of Transportation official.