hwys Interstates, e.g.: Abbr Some GPS routes Rte. 66 and others Rds. without traffic lights Limited-access rds Interstate rds I-15 and I-40, e.g Heavy lines on maps: Abbr DOT concerns Cousins of rtes "I-" rds., e.g Jct. joiners Rtes. Major rtes. Some map lines: Abbr. Cousins of rtes. Numbered rds Major rtes Major rds Roads with nos Interstates: abbr