A new study released from the University of Maryland shows more than 35% of traffic lights are inefficient. That means drivers could be wasting gas sitting at lights. In Little Rock, traffic engineers say they use state of the art computer systems to make sure traffic flows as quickly as possible. Streets are ranked by the number of cars that drive down it each day. Broadway in downtown Little Rock is one of the highest priority, so lights are timed to move cars through as fast as possible. Spring Street, on the other hand, is one of the lower priority streets, so cars are more likely to get hung up at red lights. City engineers say they`re constantly assessing the traffic flow on the streets to see if the lights need to be adjusted. They say they look at each street in the city at least once a year.